An optical disk drive is designed to read and/or write data from/on a spiral string of tracks where land and groove tracks are alternated. The drive includes: a light source for radiating a light beam; a lens for converging the light beam; a mechanism for moving the lens; a photodetector for generating an electrical signal based on at least a part of the light beam reflected from the optical disk; and a control section for controlling the light source and the mechanism responsive to the electrical signal. While performing a seek operation by having the lens moved by the mechanism such that a target track, from/on which the data should start being read or written, is irradiated with the light beam, the control section tries to get a PLL locked by irradiating another track, which precedes the target track by at least one, with the light beam.