To enable a parallel optical transmitter to be improved in channel uniformity, where a plurality of channels are arranged in parallel in the parallel optical transmitter, and bias currents each fed to laser diodes(LD) assigned to the channels respectively are collectively controlled by a common bias control circuit.

A multi-channel parallel optical transmitter 20 includes LD drive circuits 21a to 21n, LDs 22a to 22n, bias transistors 24a to 24n, and a common bias control circuit 29. The bias currents of the bias transistors 24a to 24n are set at optimal threshold currents for instance by programming (weighting) emitter resistors 26a to 26n, corresponding to the heat distribution characteristics of the LD 22a to 22n.