To provide a constant current circuit which operates stably and can supply a constant current in accordance with the control signal voltage even when the input/output characteristic of a control transister or a wiring resistance varies.

This circuit consists of the modules 10a-10j of the same constitution, and a constant current is supplied to a load terminal 2 in accordance with the control signal voltage supplied to a control input terminal 1. In each of the modules 10a-10j, the drain of an Nch type MOS transistor Tr1 is connected to an output terminal 12 and an operational amplifier 15 is connected to the gate of the Tr1. A source current I1a is detected by a current detection resistance R1 and a differential amplifier 16, controlled by the negative feedback action of the amplifier 15 and not affected by a wiring resistance R2a. The negative feedback is carried out on each module to keep the constant control characteristic of the module. Therefore the current I1a has no variance despite the variance in the input/output characteristic of the Tr1. Thus, the Tr1 never exceeds the highest bonding temperature nor the highest drain current standard.