A disk clamp apparatus includes a first centering member for positioning a center of a first side of the disk set on the turntable, a clamper member provided so as to be opposed to the first centering member across the turntable and the disk, an attraction force generating mechanism for clamping the disk on the turntable by attraction force, a clamper member turning mechanism for turning the clamper member in order to change over a clamp mode between a first clamp mode in which the disk is clamped with the first side of the disk centrally positioned, and a second clamp mode in which the disk is clamped with the second side of the disk centrally positioned. The clamper member includes a disk supporting part for supporting a second side of the disk when the first side of the disk is centrally positioned by the first centering member, and second centering mechanism for centrally positioning the second side of the disk. The second centering mechanism cancels the centering operation with respect to the first side of the disk by the first centering means, and centrally positions the second side of the disk by the attraction force when the first clamp mode is switched to the second clamp mode.