Abstract: A slot-in type optical disk-loading apparatus includes first and second housings defining a disk slot. When a large diameter optical disk is inserted into the slot so that it is supported on a roller, a motor is activated to rotate the roller so as to move the optical disk rearwardly. The large diameter optical disk pushes two front limiting members away from each other so that two rear limiting members are removed from a disk path, thereby permitting the large diameter optical disk to move rearwardly into a disk holder unit along the disk path through a space between the front limiting members. When a small diameter optical disk is inserted into the slot, it is moved rearwardly into the disk holder unit through the space between the front limiting members and a space between the rear limiting members.