An electric power converter facilitates performing soft switching in the two-way electric-power-conversion operation thereof, and reducing the manufacturing costs thereof and the losses caused therein, The electric power converter includes a first switching device; a second switching device; a first series circuit including capacitor, a diode, the primary winding of transformer, and a third switching device; a second series circuit including a capacitor, a fourth switching device, the primary winding of transformer, and a diode; a third series circuit including a diode and the secondary winding of transformer; and a voltage clamping element connected in parallel to the primary winding of transformer. The first series circuit is connected in parallel to the first switching device, and the second series circuit is connected in parallel to second switching device. The third series circuit is connected between the DC output terminals.