A main transformer is arranged such that a load is connected to its secondary winding side. A first error amplifier generates a feedback signal that corresponds to the difference between a detection signal which indicates the electrical state of the load and a predetermined first reference voltage. A current generating resistor is arranged between a current generating transistor and a fixed voltage terminal. A second error amplifier is arranged such that the first input terminal receives the electric potential at a node that connects the current generating transistor and the current generating resistor, a predetermined second reference voltage is input to the second input terminal thereof, and the output terminal thereof is connected to the control terminal of the current generating transistor. An adjustment resistor is arranged between the output terminal of the first error amplifier and a node that connects the current generating transistor and the current generating resistor.