Conventional disk recording and reproducing apparatuses have addressed a shortcoming that they cannot correct squareness errors and misalignments caused by the warpage of a disk and the eccentricity of the center hole of the disk and of the center of curvature of signal tracks. To overcome this shortcoming, a disk recording and reproducing apparatus of the present invention comprises: magnetic bearing means capable of supporting a rotary body and adjusting a relative position of the rotary body; a pickup for irradiating, with a laser beam, a recording surface of a disk mounted on a table arranged on the rotary body and receiving the laser beam reflected by the recording surface; detection means for calculating a relative positional relationship between the disk and a focal position of the laser beam based on a signal from the pickup; and control means for adjusting the position of the rotary body by controlling the magnetic bearing means.