PURPOSE: To improve the safety in lamp inspection by providing a connector for connecting a flash lamp to the output side of a high voltage generating circuit for the flash lamp and passing a line connected to the input side of the circuit through the connector.

CONSTITUTION: A power unit 1 is provided with a male type input connector 2M and a male type output connector 3M. An AC power source 4 is connected to a female type input connector 2F connected to the connector 2M. One couple of terminals of a female type output connector 3F are connected to the flash lamp 7, and the other couple are connected to a jumper line 11. A power line 5A is connected to a boosting circuit 12 through connectors 3M and 3F and line 11, and a power line 6A is connected to a circuit 12 directly. When the connectors 3M and 3F are separated so as to replace the lamp 7, the power lines 5A and 5B are disconnected from each other and no electric power is supplied to the circuit 12. Consequently, the safety is improved without changing internal circuits of the power unit.