A driver IC which is operated by a power supply system insulated from a control IC is mounted in the vicinity of a switching element on a first conductor pattern. A second conductor pattern connected to a source terminal or an emitter terminal of the switching element is electrically connected to a third conductor pattern on which the driver IC is mounted. A ground terminal of the driver IC is electrically connected to the third conductor pattern, and a drive terminal of the driver IC is electrically connected to a gate terminal or a base terminal of the switching element.