PURPOSE: To improve the margin of time axial direction to a code error as well as the S/N margin by recording a digital signal directly to a magnetic recording medium after modulating it into a biphase signal and transmitting the biphase signal through an integration circuit after converting it into the digital signal with limit amplification in a reproduction system.

CONSTITUTION: The signal reproduced from a magnetic recording medium 100 by a magnetic head 200 is amplified when necessary by a reproduction amplifier 3 and undergoes the equalization of waveform through a reproduction equalizer 4. Then the limit amplification is given to the signal underwent the equalization of waveform through a limiter or a comparator 5, and a zero cross point having the minimum effect of the interference of waveform, the level variation and the noise respectively. The signal is transmitted through an integration circuit 6 to undergo the limit amplification again through the limiter of a comparator 7. A decoding circuit 8 demodulates both the data and the clock of a digital signal and delivers them to output terminals 30 and 40 respectively. Thus the digital signal can be transmitted faithfully. In this way, the margin of the time axial direction to the discrimination of code is improved as well as the S/N margin.