In a REC mode of an ordinary image pickup standby state, a main capacitor is connected to a side of a step-up/charging circuit via a switch, and the main capacitor is charged with electric power of a charging battery. When the REC mode is changed to other modes, the main capacitor is connected to a side of a step-down circuit by a switching operation of the switch. The step-down circuit steps down charging voltage of the main capacitor to 4.2 V to supply it to a power supply circuit of a camera, and steps down the charging voltage to 5 V to supply it to the charging battery which is a power supply of the camera. When it is no longer necessary to emit fill light, the electric power lost from the main capacitor due to natural discharge can automatically be utilized efficiently for operations other than the emission of the fill light.