Cubanite occurs in the contact-metasomatic No.2 Shinyama copper deposit of Kamaishi Mine. The lump cubanite is observed abundantly in paragenesis with pyrrhotite, chalcopyrite and pentlandite, more rarely with pyrite, sphalerite and vallerite, and often intimately intergrown with chalcopyrite, pentlandite, pyrrhotite and sphalerite due to the unmixing of solid solution between them. The chemical analysis gives: Cu 23.30; Fe 41.23; S 34.81; Ni 0.11; Zn O.03; SiO2 0.51, and the X-ray powder data were given.