A disk centering system includes: a disk mount portion having a disk mount surface on which a disk form recording medium is to be mounted, the disk mount portion being provided with a predetermined reference point; and at least three disk centering portions for pressing the outer circumferential edge of the disk form recording medium, the disk centering portions being located in radial directions with the reference point as a center, wherein each of the disk centering portions can be moved between a centering position at which the disk centering portion makes contact with the outer circumferential edge of the disk form recording medium mounted on the disk mount surface to thereby center the disk form recording medium and a stand-by position located on the outer side relative to the centering position, and the centering positions are located at an equal distance from the reference point in the radial directions with the reference point as a center.