PURPOSE: To obtain dual optical communication equipments which have a high reliability and are inexpensive by using optical couplers instead of optical switches.

CONSTITUTION: A first laser diode LD 10 and a first LD driving part 30 out of first and second dual LDs 10 and 20 and first and second LD driving parts 30 and 40 which drive them are operated as the current side, and the second LD 20 and the second LD driving part 40 are stopped as the stand-by side. A control means 50 monitors the output current of the LD driving part 30; and if the driving current of the LD 10 is reduced to a prescribed value or lower, the control means 50 judges the LD 10 to be degraded and outputs a control signal to stop the LD driving part 30 and outputs a control signal to start the operation of the LD driving circuit 40 stopped till then. An optical output coupling means 60 couples optical outputs of first and second LDs 10 and 30 and outputs the result. Thus, the reliability is improved and the cost is reduced.