PURPOSE: To stably detect a peak pulse by detecting the level of a regenerative signal in positive and negative separately and restoring a pulse lack signal generated when the same polarities are detected continuously.

CONSTITUTION: The regenerative signal from the magnetic head 1 is amplified to a prescribed level through an amplifier 2, a filter 3, and after a noise is eliminated and a waveform is corrected, differential/zero crossing detection is performed through a differentiator 4, a comparator 5, a pulser 6 and made to be a park pulse. On the other hand, the regenerative signal passing through the amplifier 2, the filter 3 is level-compared by a threshold value voltage VR being the output of reference power source 7 and the comparators 8, 9, and when the level is larger than the VR a positive polarity or a negative polarity level detection pulse is generated. By utilizing that in the regenerative signal, the positive polarity and the negative polarity appear alternately in a magnetic recording and reproducing system, when the positive polarity and the negative polarity do not arrive alternately but arrive continuously as a level detection result, an inverse polarity pulse is present between them surely, by adding the pulse between them, the eliminated pulse is restored.