PURPOSE:To prevent the damage of a secondary circuit at overdrive of a switching element at a standby state and at a fault by detecting the operating state of a television receiver, transmitting the information to the primary side of the regulator so as to apply drive control to the regulator main body depending on the operating state. CONSTITUTION:A logic circuit receiving the output of a horizontal oscillation circuit 10 and a control signal gives an individual logic output corresponding to the normal operation of the television receiver, standby and fault. The logic output is given to a control means 50 via a photocoupler PC. Thus, when the control means 50 is in the standby, the regulator main body 60 is controlled to reduce the drive current of the switching element of the regulator main body more than that at the normal operation state. In the case of the fault, the control means 50 stops the main body 60.