PURPOSE: To provide a recording/reproducing device, whose data transfer speed is high, eliminating the possibility of enlarging the size of a circuit.

CONSTITUTION: This recording/reproducing device having a read after write function for reading out its data after a data recording operation is over is provide with an amplituide identification circuit 31, which detects the amplitude of an analog reproducing signal from a recording medium not reaching a binarized threshold value decided beforehand as an error, integrates the generating time of its error signal and identifies whether its recording is good or not in a sector based on the integrated time.