A photosensitive-recording medium cartridge includes: a photosensitive recording medium; a cartridge body including: a disk housing portion; an internal opening; and a shutter sliding face; a shutter; and a locking mechanism having a locking member, wherein the cartridge body includes a positioning groove including: a shallow groove formed in a side face thereof in the opposite direction of a loading direction of the photosensitive-recording medium cartridge; and a deep groove which is formed deeper in the shallow groove, and the locking mechanism includes a lock canceling member having an operating portion which protrudes from the positioning groove, and pushes the operating portion into the cartridge body to allow cancellation of engagement between the locking member and the shutter.