A purpose of this invention is to suppress radiation noise while
satisfying demands for higher speeds and higher image qualities of a
semiconductor laser driving device in a laser beam printer or the like. A
laser driving circuit includes a first wiring pattern and a second wiring
pattern which are connected to a main wiring pattern, a first circuit
which is connected to the first wiring pattern and has a semiconductor
laser element (7) and a laser driving device for driving the
semiconductor laser element, a second circuit which is connected to the
second wiring pattern, has a compensation element and a compensation
driving device, and compensates for noise in the first circuit, and a
common mode choke coil which is connected to the first and second wiring
patterns and selectively increases impedances to in-phase signal
components in a signal flowing through the first wiring pattern and the
first circuit and a signal flowing through the second wiring pattern and
the second circuit.