PURPOSE: To facilitate demodulation by causing oscillations at a frequency equal to a write frequency and generating pulural out-of-phase signals, finding phase differences from read pulses, and selecting a signal with the best phase and separating data.

CONSTITUTION: The oscillations 6 are caused at the frequency equal to the write frequency and plural signals 8W10 which are out of phase with one another are generated by a signal generator 7 from the oscillation output. The read pulse signal 1 and one of the plural signals 8W10 are supplied to a phase detector 2, whose detection output is sent to a selector 11. The selector 11 sends out a signal of te best phase relation among the signals 8W10 as a data separation signal 5 on the basis of the output of the phase detector 2. Consequently, an inexpensive demodulating device with good performance is composed of simple circuits.