The invention is to provide a restraining device of an optical disk drive in which a traverse is disposed. A transmission unit rotates a roller to, load/unload a disc, and drives a slider to move the roller. The transmission unit includes the restraining device moving with the roller. When the optical disk drive carries a disc, the slider moves to release the traverse and push down the roller to move the restraining device away from the vibration range of the traverse. When the optical disk drive does not carry a disc, the slider moves to restrain the traverse and release the roller to move the restraining device close to the front end of the traverse. The vibration range of the traverse is restrained to protect the gear teeth from damage.