Hyomashi (Office of Military Horses) was the institution belonged to Hyobusho (ministry of military) on the Ritsuryo system (a system of centralized government based on the ritsuryo code) of Japan. Kun (Japanese reading) was Tsuwamono no Uma no Tsukasa.
Hyomashi was to manage maki (the ground to raise horses and cattle) nationwide, war-horses, cows and horses of public and private (official duty of Meryo [Bureau of Horses] that had close characteristics to Hyomashi was mainly to feed the animals in the Imperial Court) and post horse system.
It was abolished in 808 and its duties were combined in Meryo.
Kami (Shorokuinojo [Senior Sixth Rank, Upper Grade]), one individual. Jo (Jushichiinoge [Junior Seventh Rank, Lower Grade]), one individual. Daireishi (Daihatsuinojo [Greater Initial Rank, Upper Grade]), Shoreishi (Daihatsuinoge [Greater Initial Rank, Lower Grade]), one individual for each.
Shibu (low rank bureaucrats), six individuals. Jikicho (factotum), one individual.