A kodachi (小太刀, こだち), literally translating into "small or short tachi (sword)", is one of the traditionally made Japanese swords (nihontō) used by the samurai class of feudal Japan.

Kodachi are from the early Kamakura period (1185–1333) and are in the shape of a tachi.

Kodachi are mounted in tachi style, but with a length of less than 60 cm (24 in).

[2] As a result, the kodachi was too short to be called a sword properly but was also too long to be considered a dagger, thus it is widely considered a primary short sword, unlike the tantō or the wakizashi which would act as a secondary weapon that was used alongside a longer bladed sword.

Kodachi appear to have been produced only in a certain time period by specific schools of swordmakers.