PURPOSE: To simplify the constitution and to attain ease of circuit integration by eliminating the need for a current mirror circuit in comparison with a conventional circuit and forming a circuit decreasing the number of constant current sources and transistors (TRs).

CONSTITUTION: Output TRs Q15, Q14 are turned off at a point A where an input signal E2 is applied to a terminal 3 is lower than an input signal (reference voltage) E1 fed to a terminal 4, a constant current i13 from a constant current source I13 is branched to the positions of a resistor R and a constant current source I12 via a diode D11. When the E2 is transited from the point A to a voltage B higher than the E1, the Q15 is changed from the off-state to the on-state, and the voltage difference between the E2 of the change point and the voltage E1, that is, R(i13-i12) becomes the hysteresis width 2. When the Q15 is turned on, the Q14 is also turned on, the i13 flows to the Q14 and does not flow to the D11. Further, since the D11 is biased reversely, it is turned off because the Q14 is turned on. When the E2 is lowered toward the point A, the Q15 is changed from the on to off-state, and the difference between the E1 and E2, that is, the Ri12 becomes the hysteresis width 1.