PURPOSE: To obtain the detecting circuit of less heat generation without consuming wasteful power, by controlling the stopping of a DC motor, when the input of signal showing driving current and excess current signal to a logical circuit is provided at the same time.

CONSTITUTION: By setting a wire for permitting the driving current for a DC motor 1 to flow to be a branch wire 14 from a motor relay 2, and by connecting the wire to the one side terminal of an AND gate 6, the input of signal during the driving of the motor or signal during the driving of no motor is provided. The output of a signal generating circuit 4 is connected to the other side terminal of the AND gate 6, and the input of normal signal or excess current signal is provided. Accordingly, when the input of the motor driving signal(1) and the normal signal(1) to the AND gate 6 is provided, then earth is connected to the motor relay 2 by a motor controlling circuit 5, and the DC motor 1 is driven. When the excess current signal(0) is detected, then the output of the AND gate 6 is turned into (0), and by the motor controlling circuit 5, the earth of the motor relay 2 is interruption-controlled, and a contact is opened, and the driving current to the DC motor 1 is interrupted and stopped the motor.