To provide a semiconductor device for controlling electric conduction to a load by switching of a semiconductor switch element, which has excellent mountability in a simple structure which avoids damages on a control IC even in the case where reverse connection of a power supply occurs when a control power supply (+B) and a power supply (BATT) are common in order to reduce wiring cost.

A semiconductor device comprises a reverse connection protection diode 102 and/or a current limit resistor 102b which are integrally formed inside a semiconductor switch element 10 as a reverse connection protection element, and connected to a control power supply terminal +B of a control IC 11 through a control power supply terminal D2 branched off from a drain terminal D of the semiconductor switch element 10.