A disk stopper (101) for regulating a loading position of the disk stopper, a stopper regulating member (102) that regulates a movable range of the disk stopper (101), and a link member (103) movable in association with the stopper regulating member (102), and a cam slider (30) engageable with the link member (103) are provided. When a small-diameter disk is inserted, the first engaging portion of the link member (103) and the first engaging portion of the cam slide (30) engage each other. When a large-diameter disk is inserted, the second engaging portion of the link member (103) and the second engaging portion of the cam slide (30) engage each other. Based on the engaging condition of the link member (103) and the cam slider (30), the stopper regulating member (102) switches the loading position of the disk medium regulated by the disk stopper (101).