To provide an emphasis circuit capable of compensating an attenuated signal by adding an emphasis effect to an edge portion of an input signal of a square wave.

In the emphasis circuit for adding the emphasis signal for compensating the attenuation of the square wave signal to the square wave, the square wave signal added the emphasis signal has a waveform for maintaining an original voltage level of the square wave signal after a lapse of predetermined falling time following a rising edge, or after a lapse of predetermined rising time following a falling edge.