PURPOSE: To enhance an effect in retest, in reading recording information in a magnetic recorder.

CONSTITUTION: This device is provided with an equalizer 4b compensating a waveform in a signal read from a recording medium, a signal detection circuit 7 converting the signal compensating the waveform to a pulse line and an equalizer control circuit 5 controlling the equalizer 4b corresponding to a retest command outputted from a host device 10. At the time of normal reading, waveform compenesation is performed in a prescribed condition and the signal is detected, but at the time of retest, the signal is detected by changing a condition in waveform compensation by the equalizer 4b. Thus, the effect in the retest is enhanced.