An MOS integrated circuit for driving light-emitting diodes (LED's) comprises first constant current circuits, each of which is for one of the LED's and includes a first drive circuit for maintaining the drive current for the associated LED at a predetermined value established by a first reference voltage. The integrated circuit further includes a second constant current circuit which is connected to all of the first constant current circuits to form a mirror circuit with each of said first constant current circuits. A current detecting element detects a predetermined magnitude of current flowing therethrough and develops a current-representative detection voltage. A second drive circuit within the second constant current circuit responds to the detection voltage and a second reference voltage by maintaining said first reference voltage at a predetermined value so that the LED drive current is determined by the said detection voltage and second reference voltage.