An electric injection molding machine includes a motor driving circuit for driving a motor, and a delivery pipe. The motor driving circuit includes a rectifier circuit, a switch control circuit, a heater, a direct current (DC) link circuit, and an inverter circuit. The switch control circuit is configured for controlling the motor to output a regenerative current generated in a deceleration period of the motor. The heater is configured for receiving the regenerative current to heat the delivery pipe via the switch control circuit. A micro control unit (MCU) outputs a heat control signal according to the voltage from the DC link circuit to turn on the switch control circuit so as control deceleration of the motor such that a regenerative current from the motor is supplied to the heater to heat the delivery pipe.