Inka (Certification of achievement) (印可)

Inka refers to the license which a master grants to a disciple who has mastered his teachings.

The written document issued as a certificate is called inkajo. Inka means the state of so-called "osumi-tsuki" (with endorsement).

In the Zen sect, a disciple who was acknowledged as having attained enlightenment had his master's portrait drawn by a painter; the master then wrote his preaching on the portrait based on the style of Chinese poetry called "gemon", and this portrait was used as a kind of diploma. Similarly, inka are given to pupils in martial arts (such as the art of swordmanship, spearmanship, and Japanese traditional self-defense martial arts), sado (tea ceremony), sanjutsu (arithmetic), and the like.

Some of the inkajo which remain today have been designated as national treasures and cultural properties.