A signal waveform equalizer circuit capable of equalizing the waveform of an input signal with a center voltage of 0 V and yet small in circuit scale. An input signal (in FIG. 1, positive-phase input signal) whose waveform is to be equalized is input to the source of an nMOS, and this enables the equalizer circuit to handle an input signal with the center voltage 0 V without the need to add an extra circuit. The waveform of the input signal is shaped by a delay circuit including a resistor and a capacitor, and an output signal (in FIG. 1, positive-phase output signal) is output from a node.