A power device for an automotive vehicle includes an interlock switch 1, a crash sensor 2 for detecting an impact of an automotive vehicle, an interlock relay 3 controlled and turned ON and OFF by the interlock switch 1, and a contactor 4 for interrupting an output circuit 11 when the interlock relay 3 is turned OFF. In the power device, when the interrupting signal is outputted from the crash sensor 2, or when the interlock switch 1 is turned OFF from ON, the contactors 4 are turned OFF to interrupt the output circuit 11. Further, the power device has a switching element 6 connected to exciting coils 4a of the contactors 4 in series and is turned ON and OFF by an interrupting signal from the crash sensor 2. When the crash sensor 2 outputs the interrupting signal, the contactors 4 are turned OFF by the switching elements 6.