PURPOSE: To facilitate the setting of the width of a hysteresis voltage by providing two variable current sources, a current switch switched in response to an output of a comparator circuit and a current polarity inverting means.

CONSTITUTION: The current switch S1 changes over whether an output current of the 1st variable current source I1 is supplied to a noninverting input of the comparator circuit 2 via a resistor R1 or supplied directly in response to an output of the comparator circuit 2. Moreover, a current mirror 1 receives an output current of the 2nd variable current source I2 and outputs a current inverting its polarity to a noninverting output of the comparator circuit 2. Since the hysteresis comparator is formed in this way, the width of an optional hysteresis voltage is set easily by having only to control the output current of the 1st and 2nd variable current sources I1, I2.