To set an offset voltage at an optional value without deteriorating a characteristic even in an input voltage near GND by adding a drain grounding circuit consisting of a constant current source capable of varying a current through trimming and of an enhancement type P-MOS transistor to the respec tive input of a differential amplifier circuit.

This circuit is constituted of a differential pair 100 composed of enhancement type P-MOS transistors 102 and 103 and a current mirror circuit 101 composed of enhancement type P-MOS transistors 104 and 105. Further, drain grounding circuits 107 and 108 consisting of constant current sources 109 and 110 capable of varying a current by trimming utilizing a laser or the like and of enhancement type P-MOS transistors 102 and 103 for level shifting are added. The enhancement type P-MOS transistor 102 or 103 of the differential pair 100 is not turned to an unsaturated state.