Disclosed herein is a disk clamping device capable of preventing the slipping or eccentricity of an optical disk when it rotates at high speeds. The disk clamping device includes a turntable having a hub which is integrally provided in a central portion thereof and inserted into a central hole of an optical disk. A guide unit is accommodated in the turntable in such a way as to move linearly, and at least portion of the guide unit protrudes outwards from the hub and is supported 0by the optical disk. The guide unit is moved linearly by mounting force of the optical disk. A spring is provided in the turntable to elastically bias the guide unit in a direction opposite to a direction of insertion of the optical disk. A chucking plate presses the upper surface of the optical disk, thus securing the optical disk to the turntable.