A power converter for rolling stock comprising: a filter capacitor that smooths a DC voltage; a plurality of power switching elements that convert a DC voltage into an AC voltage; a cooling unit that cools the power switching elements; and a conductor bar that electrically connects the filter capacitor, the overvoltage protection device, and the power switching elements, characterised in that: the power converter further comprises an overvoltage protection device that releases charge accumulated in the filter capacitor, the overvoltage protection device comprising: a DC voltage detector that detects a voltage accumulated in the filter capacitor, a power switching element for overvoltage protection device switched to ON when the charge accumulated in the filter capacitor is released, and a drive circuit that controls drive of the power switching element for overvoltage protection device; the overvoltage protection device is provided adjacent to the filter capacitor and does not include a snubber circuit, the overvoltage protection device, the filter capacitor and the power switching elements are sequentially arranged from one side, and the conductor bar has a thin flat plate shape, and is placed along surfaces of the filter capacitor and the overvoltage protection device, whereby the length of the conductor bar between the overvoltage protection device and the filter capacitor is so short that the conductor bar has a substantially zero inductance. a filter capacitor that smooths a DC voltage; a plurality of power switching elements that convert a DC voltage into an AC voltage; a cooling unit that cools the power switching elements; and a conductor bar that electrically connects the filter capacitor, the overvoltage protection device, and the power switching elements, characterised in that: the power converter further comprises an overvoltage protection device that releases charge accumulated in the filter capacitor, the overvoltage protection device comprising: a DC voltage detector that detects a voltage accumulated in the filter capacitor, a power switching element for overvoltage protection device switched to ON when the charge accumulated in the filter capacitor is released, and a drive circuit that controls drive of the power switching element for overvoltage protection device; the overvoltage protection device is provided adjacent to the filter capacitor and does not include a snubber circuit, the overvoltage protection device, the filter capacitor and the power switching elements are sequentially arranged from one side, and the conductor bar has a thin flat plate shape, and is placed along surfaces of the filter capacitor and the overvoltage protection device, the power converter further comprises an overvoltage protection device that releases charge accumulated in the filter capacitor, the overvoltage protection device comprising: a DC voltage detector that detects a voltage accumulated in the filter capacitor, a power switching element for overvoltage protection device switched to ON when the charge accumulated in the filter capacitor is released, and a drive circuit that controls drive of the power switching element for overvoltage protection device; a DC voltage detector that detects a voltage accumulated in the filter capacitor, a power switching element for overvoltage protection device switched to ON when the charge accumulated in the filter capacitor is released, and a drive circuit that controls drive of the power switching element for overvoltage protection device; the overvoltage protection device is provided adjacent to the filter capacitor and does not include a snubber circuit, the overvoltage protection device, the filter capacitor and the power switching elements are sequentially arranged from one side, and the conductor bar has a thin flat plate shape, and is placed along surfaces of the filter capacitor and the overvoltage protection device, whereby the length of the conductor bar between the overvoltage protection device and the filter capacitor is so short that the conductor bar has a substantially zero inductance.