An apparatus for electric power conversion in an electric rolling stock, comprising an inverter which receives a DC power fed from a DC power source at DC terminals, converts the received DC power into an AC power, and supplies the AC power to an AC motor, a first capacitor which is connected to the DC terminals of the inverter by low inductance connection and reduces a surge voltage generated in the inverter, and a second capacitor which is connected to the DC terminals of the inverter through a fuse, wherein a total sum of capacities of the first and the second capacitors is equal to or larger than a system demand capacitance.