An optical transceiver is disclosed in which the optical output thereof is controlled without degrading the signal quality. The optical transceiver of the invention includes a plurality of transmitter units and a controller that adjusts the bias current of respective transmitter units. The controller, receiving information to decrease/increase the output of the optical transceiver, decides a unique unit that has a largest margin to increase/decrease the bias current and provides a control signal only to the unique unit to increase/decrease the bias current.