PURPOSE: To obtain a small size and maintenance-free power converter for vehicle by employing a noncontact contactor, i.e. a thyristor, in the discharge circuit for capacitor and connecting the thyristor in series with the thyristor in an overvoltage suppressing circuit.

CONSTITUTION: A power convertor for vehicle comprises a capacitor 7 to be charged with power fed from a pantograph 1 and a voltage detector 11 and thyristor 20 connected in parallel therewith. Upon interruption of the operation of a converter 6, the thyristor 20 is turned ON through a gate circuit 22 thus discharging the capacitor 7. When a voltage detector 11 detects overvoltage across the capacitor 7, a protective logic circuit 23 turns the thyristors 14, 20 ON simultaneously through gate circuits 16, 22 thus discharging the capacitor 7 quickly. Since the noncontact thyristor 20 is employed in the discharge circuit, maintenance is not required and the size is reduced.