An optical disk drive includes: a tray having first and second loading portions for respectively loading a first disk and a second disk of a smaller diameter than the first disk, the first and second loading portions having different heights, first and second inclined portions formed obliquely outward and inward on edges of the first and second loading portions, respectively. The optical disk drive further includes: a spindle motor having a turntable supporting the disks on a plane thereof, the motor rotating the disks and approaching/departing from the disks; and a clamp rotatably supporting the disks on the other plane thereof, wherein the clamp can approach the disks due to a magnetic force exerted between the clamp and the turntable as the spindle motor approaches the disks.