PURPOSE: To prevent the unwanted running of the electric car beforehand by detecting the fused contact of a contactor which connects a power source and a motor at the starting of the electric car and inhibiting the operation of a power supply control circuit when the fused contacted is detected.

CONSTITUTION: When an accelerator switch 6 is turned on in starting the electric car, a capacitor 15 begins to be charged by the output of a comparator 10. Then, the output of the other comparator 11 becomes a 1, transistors 12 and 14 are turned ON, a transistor 13 is turned OFF, and the signals of a trigger circuit 50 and a chopper 3 are cut out. When a specified time has elasped after the accelerator switch was turned ON, the transistor 13 is turned ON, the contactor 4 is closed, the trigger signal is supplied to the chopper 3, and the power supply control begins. If the contactor is closed when the accelerator switch is turned ON, the output of the comparator 10 continues to be a 0, the capacitor 15 is not charged, the output of the comparator 11 is a 1, and the transistor 14 remains ON.