A card cassette device ensures elimination of measures for illegally opening a card outlet from the outside in a non-mounted state and makes it possible to open the card outlet according to the necessity in a mounted state, raising security level. A movable shutter for opening and closing a card outlet has a stopper member engaging hole and a lock member engaging hole. A stopper member is engaged with the stopper member engaging hole by a stopper member moving device, thereby fixing the shutter in its closed state in the non-mounted state. A lock member is engaged with the lock member engaging hole by a lock member moving device, thereby canceling the closed state of the shutter and locking the shutter in its open state in the mounted state.