PURPOSE: To record an abrupt accident speedily and accurately by providing an auxiliary switch which moves in interlocking with a recording switch and turning on for a specific time to hold a self-holding circuit in a holding state.

CONSTITUTION: When an auxiliary switch 19 is tuned on, a power is supplied to a resistor 20 and a capacitor 21, whose charging voltage turns on a transistor 24 through resistors 22 and 23 constituting a biasing circuit; and a relay circuit 6 is placed in a held state and a switch 8 is turned on. At this time, a power terminal 1, the power terminal 11 of a recording device, and the power terminal of a system controller 10 are connected mutually and electrically to supply the power to the recording device and system controller 10. Further, a recording switch 9 is operatively associated with the auxiliary switch 19, so it is turned on to instruct the recording device by the system controller 10 to start recording.