PURPOSE: To enable to perform the reductions in the weight and size of an optical integrated circuit having a photoamplifying function by forming a light emitting element and two FETs on the same substrate, and providing the functions of a receiver and an amplifier in one FET.

CONSTITUTION: A semiconductor laser having a P type InP clad layer 2, a P type InGaAsP active layer 5, and an N type InP layer 8; the first junction type FET having a source 7, a gate 9, a drain 12, and the second juction type FET having a source 10, a gate 11 and a drain 13 are formed on an InP semi-insulating substrate 1. The first FET is a semiconductor laser driver, a suitably voltage is applied to the gate 11 of the second FET to flow a current amplified by the light signal from the exterior. In this manner, the laser produces a laser produces a laser oscillation, and the light signal incident from the exterior is amplified.