According to the power shutoff method for the TCPIP network device, the connection status of the terminal connected to the TCPIP network is monitored, whether the power can be shut off or not is judged based on the result of the monitoring, and the power for the terminal is shut off when it is judged acceptable to shut off the power in the judgment step. According to the method, there is detected when a change of a load applied to an output terminal of the converter occurs. The edge portion abuttingly engages an extension of the firing pin adapted to be in planar movement with the edge portion of the sear.