A torque control device for an electrical tool has a switching circuit, a voltage detecting circuit, a torque detecting circuit and a processor. The switching circuit connects between a motor of the electrical tool and a DC voltage source. The voltage detecting circuit detects voltage or current variation of the motor. The torque detecting circuit based on the detected voltage or current variation data outputs an actual torque value of the motor. The processor compares the actual torque value with a default value to determine whether actual torque is greater than the default. If so, the switching circuit is turned off by the processor to prevent the motor from being damaged.