A semiconductor device includes a current control unit whose conductance is variable and a control unit configured to control the conductance of the current control unit. The current control unit is connected to a direct current power source in parallel with a load for the direct current power source, through a capacitor. The control unit sets the current control unit to a first conductance when the direct current power source and the load are not in a conduction state, and sets the current control unit to a second conductance larger than the first conductance when the direct current power source and the load are in the conduction state.