A power converting device for an electric train includes a power converter, an alternating-current motor, a primary control unit, and a control unit. The power converter converts direct-current power into alternating-current power. The alternating-current motor is driven by the alternating-current power output from the power converter. The primary control unit outputs a power-running notch command that determines an acceleration speed for the electric train. The control unit controls an amount of the alternating-current power based on the power-running notch command. The control unit sets the amount of the alternating-current power to zero without a delay after receiving an OFF signal of the power-running notch command during power running.