An optical disk device generating reproduced data based on a reproduced digital signal which is derived by tracking a track on an optical disk with an optical pickup is shown. A bit-frequency-information generation unit measures a bit frequency of the reproduced digital signal after transition of the optical pickup in a seek operation, and generates measured-bit-frequency information which indicates a measured bit frequency measured thereby. In a bit-frequency setting unit, if there is a difference between the measured bit frequency and a specified bit frequency, the measured-bit-frequency information is corrected so as to adjust the bit frequency of the reproduced digital signal to the specified bit frequency by a given amount of correction, and is produced as setting-bit-frequency information. And a PLL circuit generates a synchronization clock which is phase synchronized to the reproduced digital signal and is used for generation of the reproduced data by means of setting the bit frequency indicated by the setting-bit-frequency information to a free-run frequency of the PLL circuit.