PURPOSE: To enhance the reliability for the wavelength multiple optical communication device by reducing the average lighting time of the electricity-light conversion element.

CONSTITUTION: The clock and the input NRZ signal of the 50% duty factor are converted into signals 87 and 88 of the 25% duty factor via logic 1 and 0 sampling circuit 8 to be changed into the optical signals of different wavelengths with driving of electricity-light converter circuits 1 and 2 and then transmitted to optical cables 41 and 42. these optical signals are received at light-electricity converter circuits 6 and 7 of the reception side through wave compounder 3, optical cable 43 and branching filter 5 each and then regenerated through logic 1 and 0 compounding circuit 9. Here the average lighting time of light emitting diodes 13 and 23 in circuits 1 and 2 becomes equal to the duty factor of the input signal to be about half of the conventional time. As a result, the using time can be increased for the diode.