Keicho Koban (oval coin) (慶長小判)

Keicho Koban had been issued since 1601, during the early period of the Edo period,and was currency by table having one Ryo value per one Koban. Keicho Koban and Keicho Ichibuban are called Keicho Kin,and generally, Keicho-Oban is also included. Keicho Chogin and Keicho Koban are called Keicho Kingin (gold and silver of Keicho), having vital importance as the early currency by Edo bakufu (Japanese feudal government headed by a shogun), representing domination of the whole country by Ieyasu TOKUGAWA.

One theory has it the first casting of Keicho Kin (Keicho gold) was the same time when gin-za (literally, silver za, or silver mint) was built and the casting of Keicho Gin started, establishing currency system in 1601, the other has it the casting had already started in 1600.


It has chiseled mark like straw matt on its head, there are fan shape frame above and under the Kiri-mon (paulownia patterns), hallmark of 'Ichiryo' on upper part of the center and of Mitsutsugu (Kao [written seal mark]) on lower part, Kao (written seal mark) on the center of the tail, test hallmark of Kobanshi (a Koban master) on the right or left part of lower part, and test hallmark of Fukisyo (in where Koban were casted). Many kobans have only one test hallmark of Kobanshi without that of Fukisho. The Kao (written seal mark) on the tail is bigger than that of Shotoku Koban or Kyoho Koban and simple on the whole.

Keicho Kobans with fine straw matt mark were casted in the early period and the ones made coarsely and uniformly resembling Genroku Koban (oval coin) were thought to be cast in the late period, after the Great Fire of Meireki, and during about 95 years of issuance of Keicho Koban, it was presumed that it was cast in large number in the eary period, but became less in the late period according to the declining volume of gold production, and actually now more Keicho Koban in the late period remain.

They are sometimes classified according to hallmark of casting into 'Edoza', 'Kyoza' or' Surugaza', however, it has no evidence and the classification according to casting site is unknown.

Brief history

Ieyasu TOKUGAWA, who had won the Battle of Sekigahara, made the improvement of currency system one of the most important tasks before the foundation of Bakufu, ordering Shosaburo Mitsutsugu GOTO to cast Koban which were supposed to be circulated across the country. In the the Keicho Period, Kobanshi leaded Fukiya craftmen, submitting bankin (gold coins) they had made to Goto office, selling it to exchanger after correcting a carat and ryome (a weighed value) and having hallmark printed on it, which was called the form of Temaebuki. Goto office and Kobanza got to be called as kin-za (literally, gold za, or gold mint) later.

Edo bakufu improved three currency system (Koban, Chogin [collective term of silver]and coin) to unify the currency of the whole country: it consited of the existing currency circulation; hallmark silver which was a silver-by-weight standard used by mainly merchants in Osaka and Torai-sen (imported currency from China) used among commers, and the currency unit, 'Ryo' 'Bu' and 'Shu', based on quarternary system of Koshu gold which was cast by the order of Shingen TAKEDA whom Ieyasu looked up to.

Koban was circulated mostly in Kanto region around Edo as it was called 'financial habit of Edo', because in Togoku, there were many gold mines such as Kurokawa Kinzan (Kurokawa Gold Mine) in Kai Province, Doi Mine in Izu Province, Hitachi Province and Mutsu Province, in addition, the preparation of metal for currency casting was completed as Insu gold was imported mainly from China against the outflow of the large sum of silver from Japan in the early Edo period, and Ieyasu planned to make gold basic currency after the Koshu gold. One of the reasons why Koban was circulated around Edo was there were many samurai residences in Edo and high-ranking warriors used mainly Koban in a large amount transactions. Like that, Ieyasu's ideal was the unification of the currency of the whole country using currency unit'Ryo' based on Koban, however, he was forced to follow the existing system due to cumbersome calculation of quaternary and powerful merchants who used a silver-by-weight standard for real value reasons who couldn't be supressed by authority.

In 1609, bakufu decided the market price of three currency as 1ryo=silver 50 monme = Eiraku-tsuho (bronze coins struck in the Ming dynasty) 1 kanmon=Bitasen (low quality coins whose surfaces were worn away) 4 kanmon, however, it was introduced just as criterion and in reality, it was flexible rate which was left to market, and was intervened by the government in the case that the rate went too far. And in the previous year, 1608, furegaki (bakufu orders) which banned the use of Eiraku-tsuho (bronze coins struck in the Ming dynasty) was issued, which meant actual abolishment of gold 1ryo=Eiraku-tsuho (bronze coins struck in the Ming dynasty) 1 kanmon, making gold 1ryo=Kyosen 4 kanmon, which was set as lower zeni compared to the rate at that time: it aimed to show the authority of bakufu by setting the value of Koban high. Since 1636, bakufu had made zeni-za (an organization in charge of minting coins during the Edo period) across the country cast Eiraku-tsuho (bronze coins struck in the Ming dynasty), whose value was set the same as Bitasen (low quality coins whose surfaces were worn away), though it was good quality coin.

Casting of Koban started in Edo during the time of Ieyasu's territory currency, then kin-za (an organization in charge of casting and appraising of gold during the Edo period) was built in Kyoto around 1601, in Suruga Province between 1607 and 1616 and in Sado Province, which boasted the largest amount of gold mining. Sado ban (Sado version) had a character '佐' as hallmark of Sujimiyaku (inspector) on the place of test hallmark of Kobanshi, along with characters '神' and '当' as test hallmark of Fukisho.

The Karumekin which was broken, chipped and chafed were increasing, having been circulated more than 90 years, and such Koban was mended in kin-za (an organization in charge of casting and appraising of gold during the Edo period) by adding gold. That was called 'Honnaoshi (mending properly), with engraved mark 'Hon' on it.

In the early Edo period, Hyodo kahei (currency valued by weight) such as cupellated gold and silver which had hallmark on metal, was circulated widely, and bakufu banned cupellation of gold and silver (isolation and ore refining) in feudal lord's territories around the country in 1668, controlling major gold and silver mines as tenryo (a shogunal demesne) under the direct control of bakufu to organize territory currency like Hyodo kahei and unify them into Keicho gold and silver. However, monetary unification wasn't realized until reminting of a coin in Genroku Period.

In May 1697, furegaki (bakufu orders) saying Hyodo kahei was to be uncurrent by March of Genroku 11 (in lunar calender, which was April 1698) was issued, however, there were many people who stored away as exchange didn't progress, and in December 13, bakufu changed the date to March of Genroku 12 (in lunar calender, which was March 1699), though it couldn't make it uncurrent. In June 1738, premium class on the currency at that time was stopped once after reminting of a coin in Gembun era, however, it wasn't stopped completely as the price of premium class had been set again and again until end of Edo period.

Suruga Sumigaki Koban

Suruga Sumigaki Koban consists of a large-sized old Japanese gold coin with hammer tone resembling Tensho-Oban and a oval koban with the same style as Oban,having written 'Suruga kyoumoku ichiryo (kao)' in ink, called Kyoume Ichiryo Koban or Suruga Sumiban, and a theory has it that it was daimyos' own territory currency Ieyasu ordered to cast after he moved to Suruga Province in Tensho era, however, which is not clear. According to "Kinginzuroku" (Gold & Silver catalog) and "Dainihon Kaheishi" (Great History of Japanese Currency), it was cast in 1595, however, this was contradictory to the theory that Suruga Sumigaki Koban was initiated by Ieyasu; therefore, another theory holds that it was ordered to cast by Kazuuji NAKAMURA, vassal of Hideyoshi TOYOTOMI.

Its ryome (a weighed value) is Kyome (old Japanese unit of measure used around Kyoto) or 4 monme 5 bu as instructed in ink equivalent to the actual measurement value, 16.7 to 16.9 gram, of the one exists now.

Musashi Sumigaki Koban

Musashi Sumigaki Koban is also called Musashi Sumiban, the same style koban as Suruga Sumigaki Koban, which has 'Musashi Ichiryo Mitsutsugu (kao)' in ink, and it's shape is oval with adjusted ryome by filled metal or oblong. It was also casted in 1595 according to "Kinginzuroku (Gold & Silver catalog)" and "History of great Japan currency"(widely-accepted theory has it that it was casted in 1596), regarded as daimyos' own territory currency for Kanhasshu (the Eight Provinces of Kanto region) ordered to cast after Ieyasu moved to Edo, thought to be the original of Keicho Koban based on its ryome and gold carat. 1595 was the year in which Shosaburo Mitsutsugu GOTO went to Edo. There actually exists Keicho Koban which is thought to be recast of these Sumigaki Koban.

Its ryome is only 4 monme 8 bu (17.8gram) likely to be 4 monme 7 bu 6 rin which is defined ryome of Keicho Koban,and gold carat is only approximately 52 monme 2 bu (84.3%).


Enbukin was oval gold coin which had Kiri-mon (paulownia patterns) on the center of head, Kiri-mon of Gokasho around it, Kao (written seal mark) of Shosaburo Mitsutsugu GOTO on the center of tail, hallmark of Kiri-mon of Gokasho around it, and its western gold coin shape was unusual for Japanese gold coin. It was thought to be one of Itibuban and cast from the end of Tensho era to Keicho era, though it is not clear.

Its ryome is likely to be only 1 monme 2 bu (4.5gram) and gold carat is approximately 52 monme 2 bu (84.3%), and it was also inherited by Keicho Ichibuban.

It had been called Taiko (retired imperial regent) Enbukin once, however, the theory it was not related to Hideyoshi is prevailing now.

Gaku Ichibuban

Gaku Ichibuban is a rectangular reed-shaped gold coin with the same shape as Keicho Ichibuban. There is frame around 'Ichibu' on its head and hallmark of Mitsutsugu (Kao[written seal mark]) on the tail.

Its ryome is ouly 1 monme 2 bu (4.5gram) the same as Enbukin, gold carat is approximately 52 monme 2 bu (84.3%).

It appears to have nothing to do with Hideyoshi, though it had been also called Osaka Ichibukin once. It was casted around 1599.

Keicho Kochu Koban

Keicho Kochu Koban is defined as the early Keicho Koban, cast based on Ieyasu's plan, changing sumigaki of Musashi Sumigaki Koban to hallmark, around 1600, previous year in which the currency system of Keicho was established, supposed to be circulated publicly.

It was also called Nagakoban due to its oblong shape, irregular and minute hammer tone of U shape cross section while ordinary Keicho Koban has straw matt tone of V shape cross section, and its ryome and gold carat followed that of Musashi Sumigaki Koban, being inherited by the early Keicho Koban later.

It has many variations such as revised Musashi Sumigaki Koban and newly cast bankin (gold coins), and many theories about the time of casting, the borderline between Kochu Koban and the early Keicho Koban and others.

Keicho Nibuban

Keicho Nibuban has hammer tone and the same style as Keicho Kochu Koban, and its ryome is about half as much as it, 2 monme 4 bu (8.9gram),called also Keicho Nibukoban.

There is fan shape frame around Kiri-mon (paulownia patterns) on the upper part of its head, 'Nibu' with rectangular frame on the upper center, 'Mitsutsugu (Kao[written seal mark]) 'on the lower part, Kao on the center of tail, imprinted hallmark which likely to be Kobanshi's on the lower left, and it is thought to be like a proof coin because it scarcely exists now, one of which Mint Museum owners.


Hachiryoban is a gold coin with rectangluar frame around 'Oban' on the upper center, 'Mitsutsugu (Kao[written seal mark]) ' on the lower part, small 12 Kiri-mon (paulownia patterns) hallmarks are imprinted on outer circumference. Mint Museum and Currency Museum of the Bank of Japan own them, which are thought to be all Hachiburyouban exist now.

Its ryome is 38 monme 8 rin according to the document of Kin-za (an organization in charge of casting and appraising of gold during the Edo period), which is just 8 times as much as Koban's, 4 monme 6 rin, thus it is called Hachiryoban. The actual measurement value of existing Hachiryoban is 142.25 gram. Its gold carat is likely to be approximately 52 monme 2 bu (84.3%).

It appears to have nothing to do with Hideyoshi, though it was also called Taiko (retired imperial regent) Oban.

The document of kin-za (an organization in charge of casting and appraising of gold during the Edo period) at the time of Genroku Oban Reminting said they cast Oban by remitting 160 Hachiryoban, which is thought to be the Hachiryoban, and others.

Keicho Ichibuban

Along with Ichiryo Koban, Ichibukin whose value is one fourth of Ichiryo Koban, was cast constantly during Edo period at the same time of Koban, and its gold carat is the same as Koban, ryome is one fourth of Koban,used as standard money like Koban.

Keicho Ichibuban is a rectangluar reed-shape ichibuban with the same carat and one fourth ryome of Keicho Koban, having fan shape Kiri-mon (paulownia patterns) on the upper part of its head, 'bu ichi' in horizontal writing on the center, Kiri-mon (paulownia patterns) on the lower part, imprinted hallmark of Mitsutsugu (Kao[written seal mark]) on the tail.

There are Ichibukin called 'Katahon', which has imprinted hallmark of 'Hon' on the right part of the tail, and 'Ryobon' which has a one on the upper right and left part, which means they are 'hon-naoshi', mended Ichibuban broken or chafed by being used long time in kin-za (an organization in charge of casting and appraising of gold during the Edo period).

Ichibuban's casting time and place are also not clear, though they are classified as 'Koch' 'Edoza' 'Kyoza' 'Surugaza' and called so.

Ryome and carat of Keicho Kin.

Koban's regular ryome (mass) is 4 monme 7 bu 6 rin (17.76 gram), and Ichibuban's is 1 monme 1 bu 9 rin (4.44 gram).

That regular ryome appears to be derived as follows based on kyome 1 ryo or 4 monme 4 bu.

The raw materials of Koban is gold ten ryo (currency unit), that is silver 8 monme 2 bu added to genuine gold 44 monme considering a carat is about 52 monme 2 bu,deducting Buichikin 4 monme 4 bu from it equals 47 monme 8 bu, deducting 2 bu which is the amount reducing during the casting, making it 47 monme 6 bu. That is (52.2-4.4-0.2) ÷104.76.

The price of the Oban whose ryome is 44 monme 2 bu evaluated as 8 ryo 2 bu,10 ryo of which equals 52 monme, deducing Ichibukin 4 monme 4 bu as commission charges for kin-za (an organization in charge of casting and appraising of gold during the Edo period) equals 47 monme 6 bu, making 1 ryo equal 4 monme 7 bu 6 rin. That is (44.2÷8.5-4.4)÷104.76.

Its regular carat was around 52 monme (84.6%) in the early time (52 monme 2 bu [84.29%]is average), rising to 50 monme 7 bu (86.79%) which is 'the value of Mimasu' around the time of the 3rd Shosaburo Yoshishige GOTO, after Kanei era, later. The remnant was silver.

The content percentage of currency was top secret and analysing the currency privately was banned in Edo period. However, the exchangers analysed it using touch stone because the imformation of the contained amount of gold and silver was important for them, and it came to merchants' knowledge.

The content percentage of gold was displayed as ryome of mixed metal, adding silver to genuine gold 44 monme, for the convenience of the workplace in kin-za (an organization in charge of casting and appraising of gold during the Edo period).

For example, 50 monme 7 bu is mixed metal of gold and silver made by adding cupellated silver (genuine silver) 6 monme 7 bu to genuine gold 44 monme, and its carat is 44/50.70.8679.

In Meiji Period, the currency of Edo period was analysed by Mint Bureau (Japan). The result of Keicho Kin is as follows.

gold 86.28%
silver 13.20%
miscellaneous metals 0.52%

Miscellaneous metals consist of copper, lead and iridium. Impurity of copper is called 'douke', lead 'rouke', removing during the casting as best, and having much iridium made it difficult to cast.

The amount of cast Keicho Kin.

The currency (koban and chogin[collective term of silver]) in the Keicho Period was issued by such process as follows, goldsmiths got bare metal by themselves calling it 'Temaebuki', casting it into the shape of currency, submitting it to kin-za (an organization in charge of casting and appraising of gold during the Edo period), then, hallmark was imprinted on it to issue it. There exists no document about the correct number of casted Keicho Kin and Keicho Chogin (silver oval coin) due to the destruction of "Document of Goto Office" by fire during the Great Fire of Meireki.

On the other hand, Koban and Ichibukin were cast 14,727,055 ryo in total,estimating the amount of circulation in the country 100,000 ryo and in the foreign countries 4,100,000 ryo and the amount of the reminted coin such as Genroku Koban 10,527,055 ryo, according to " The Book of interrogation copy about the year and old high gold and silver coinage".

However,"catalogs money in Japan" estimated the amount of currency exported to foreign countries 13,024,000 ryo, adopting 2,397,600 ryo based on "Honcho Houka Tsuyoujiryaku", saying "The Book of interrogation copy about the year and old high gold and silver coinage"estimates it too high.

It appears Ichibuban was ordered to cast to account for 50% of the total amount of casting.

The amount of casting Sadoban between 1621 and 1695 is estimated about 138 ryo of koban and about 70,000 ryo (280,000 pieces) of Ichibuban.

After the Great Fire of Meireki in 1659, about 170,000 ryo of koban was cast using burnout gold and silver of Gokinzo (the treasure house in Edo-jo Castle) in third bailey of Edo-jo Castle, when koban with coarse straw matt tone was cast and it is specifically called Edoban.

And Buichikin, which was commission charges for kin-za (an organization in charge of casting and appraising of gold during the Edo period), was 10 ryo for clerk, 10 ryo 2 bu for workman of Kinza and 4 ryo for toryo (leader) of Fukisyo.