An electronic control unit for controlling an inverter mounted between a main battery and a motor in an electric vehicle includes a feed-back control device which ensures that an actual electric power calculated from an electric current and a voltage inputted to the inverter is equalized to a target electric power calculated from the motor revolution-number, an accelerator opening degree and a shift position. If a circuit between the main battery and the motor is opened during regenerative operation, so that the charging of the main battery with a regenerative electric power cannot be performed and as a result, the voltage is increased to exceed a predetermined value, a regeneration prohibiting device prohibits the regenerative operation of the motor to prevent damage to the inverter due to a counter-electromotive voltage of the motor.