A lock mechanism includes a lock member that can take a locked position in which the lock member contacts a lid to lock the lid, and an unlocked position in which the lock member is spaced apart from the lid to release the locking, a button that pushes the lock member to cause the lock member to swing to the unlocked position, and a support member that supports both the lock member and the button. The support member has a stopper for locking the lock member in the locked position. The stopper is integrated with the support member. The button is spaced apart from the lock member when the lock member is in the locked position.