The utility model relates to a protection circuit device for a power source system, which is used in ordinary circuits which is provided with a power supply system, particularly protecting switch motions of a power source. The utility model comprises an anti-bounce circuit, a selection circuit, a sustain circuit and an isolating circuit, wherein, the anti-bounce circuit receives signals which are input after a bounce switch is activated, which can eliminate misoperation possibly caused by the phenomenon of tremors generated by the input signals. The selection circuit receives outputs of the output end of the anti-bounce circuit, and outputs a signal which can control the opening and the closure of a system power source. The sustain circuit can sustain the supply of a normal working power source which is required in a follow-up connecting circuit. The isolating circuit can supply the isolation to a main power source, and can receive an input signal to imperatively turn off the system power source.