PURPOSE: To provide a port opening/closing mechanism of an optical disk driving device capable of getting a dustproof effect without increasing the quantity of parts and to provide a cartridge locking mechanism of the optical disk driving device capable of smoothly ejecting a cartridge without increasing the quantity of parts.

CONSTITUTION: By attaching a cam groove 11b for opening/closing the dustproof door to a cam plate 11 for moving a holder, the dustproof effect can be obtained without increasing the quantity of parts. Also by making lock levers 38, 52 for locking the cartridge to provide energizing forces for locking and for cartridge ejecting, a rotating force for locking the cartridge and an ejecting force of cartridge are exerted by one part without increasing the quantity of parts, and a lever spring force for opening the shutter can be reduced, then the cartridge is smoothly ejected.