A cartridge detachably attached to a printer apparatus includes a casing, an ink ribbon provided in the casing, a supply spool provided in the casing for supplying the ink ribbon, and a take-up spool provided in the casing for retrieving the ink ribbon. The printer apparatus includes a locking member rotatably supported on the printer apparatus and locking the cartridge to the printer apparatus, a detection device for detecting an installation of the cartridge by detecting a locked state of the locking member, a locking portion for locking the locking member when the cartridge is installed in the printer apparatus, and a guide forcefully and rotatingly displacing the locking member from a locking position when the cartridge is pulled out from the printer apparatus.