Two semiconductor switches are arranged in parallel in a load circuit for connecting a power source with a load. Further, the semiconductor switches are controlled so as to be alternately tuned on and off. As a result, since a current flows through only either of the semiconductor switches, an offset error detected by current sensors includes only an offset error of either of the semiconductor switches, the detection of current with high accuracy can be accomplished. Therefore, when performing the control of shutting off the circuit to cope with the occurrence of an overcurrent flowing through the load, the shutoff control with high accuracy can be accomplished.