PURPOSE: To prevent elements from being destroyed by implementing a desired sequential operation for two outputs only with the ON/OFF operation of a power switch in a power device used for a printed circuit board or the like.

CONSTITUTION: When an interlocking switch 10 is closed, an output 1 is caused to rise immediately through a first power unit 13, and is turned on. Continuously, a second relay switch 12 is closed by the driving of a second relay switch control unit 16 to cause an output 2 to rise through a second power unit 14, and is turned on. In this respect, after the output 2 is turned on, a first relay switch 11 is closed by a first relay switch control unit 15. Then, when the interlocking switch is turned off, the output 2 is immediately turned off. In continuation, the first relay switch 11 is opened by the operation of the first relay switch control unit 15, and the output 1 is also turned off. Accordingly, the required operational sequence at the time of the ON/OFF of the output 1 and output 2 is implemented by the operation of the interlocking switch 10.