A disclosed laser diode driving circuit causes a laser diode to emit light
by varying a current value of a current source in accordance with a
control signal input externally and supplying a current that is the same
as or proportional to the current value to the laser diode. The driving
circuit includes correction circuitry for generating a reference forward
voltage as a reference for the laser diode in accordance with a
predetermined driving current for driving the laser diode, generating a
forward voltage for the laser diode in accordance with the predetermined
driving current, and correcting a current supplied to the laser diode so
that the forward voltage becomes the same as the reference forward
voltage.