To make compatible low consumption power formation of a control circuit of a light emitting element and high frequency formation of operational frequency band constituting a variety of usable combination elements of light emitting elements and light receiving elements, bias current is provided to a current mirror for dividing monitor current of a photodiode PD1 by a current source to thereby compensate drive function of a post stage in driving thereof by low current. Reference voltage of a current-voltage conversion portion is set in accordance with an input range of an operational amplifier of a gain adjusting portion at a post stage and input to the operational amplifier is fitted to an input range optimizing amplifying function. There are provided switching circuits SW1 and SW2 for selectively supplying monitor current from two photodiodes to respective APC loops of laser diodes LD1 and LD2 to thereby deal with a 2LD-1PD element and two of 1LD-1PD elements.