A disk chucking mechanism constructed with first, second and third link members forms a slider crank mechanism and the third link member is rotated by a drive of a forward/rearward actuator such as an air cylinder and chucking nails are provided which protrude perpendicularly to a longitudinal direction of the first or second link member. A rotation of the chucking nail protruded perpendicularly is stopped by engagement with a disk and a spring member is bent by further forward or rearward movement of the second link member to energize a first chucking nail in a direction for maintaining an engagement with the disk. The disk is chucked with a predetermined force by only the drive of the forward/rearward actuator.