PURPOSE: To conform rotational phase automatically when apparatuses are transposed by extracting a certain fixed signal from a regenerative signal, obtaining difference with a reference signal, and adding the difference to the preset value of a phase comparison counter.

CONSTITUTION: A phase difference counter 20 counts phase difference between a certain fixed signal from a regenerative signal and a reference signal, and outputs a phase-difference count value E. When a difference between the phase- difference count value E and a phase-difference reference value F is obtained by a subtracter 24 (E-F=D: a phase shift section) and the difference section D is added to a preset value through an adder 25, a phase comparison counter 4 counts only by an interval (A-D). Accordingly, rotational phase can be conformed automatically even when rotational phase does not coincide by transposition, etc., between apparatuses.