A controller for an optical disk drive includes a modulator configured to
modulate a record data to be recorded on a optical disk based on a record
clock that is a reference clock in recording, and to generate a
modulation data and an address information of the modulation data. A
prepit decoder is configured to generate a prepit clock from a prepit
signal detected from the optical disk, and a decision circuit is
configured to determine whether or not recording in accordance with a
standard is performed, from phase characteristic based on the address
information and the prepit clock, and to control a frequency of the
record clock.