PURPOSE: To approximately and automatically equalize a received digital signal with respect to its required equalizing band width with a simple constitution in respect of a line equalizing circuit for automatically equalizing the received digital signal in accordance with line length.

CONSTITUTION: The line equalizing circuit is provided with a pulse transformer 1 for inputting a digital signal received from an input terminal 5 to the primary side and outputting the digital signal as a phase-inverted signal from the secondary side, a high pass filter 2 for adding the phaseinverted signal obtained from the secondary side of the pulse transformer 1 to the digital signal and transistors(TRs) 3, 4 for adding a phase-inverted signal obtained by cutting off a low frequency component by the filter 2 to their bases, and constituted so that the emitters of the TRs 3, 4 are mutually connected in common to obtain push-pull connection and equalized digital signals are outputted from output terminals 6 connected to the collectors of the TRs 3, 4.