Abstract: An electrical energy saving device for motors comprises in combination a principal circuit system and an associated control circuit system. The principal circuit system includes an input power source, a transducer unit, a load, and a triggering device. The control circuit system includes a signal amplifying unit, a feedback unit, a working-point adjusting and indicating unit, a rectifying and filtering unit, a photoelectric coupling unit, an overload protecting unit, and a delay protecting unit. The control circuit system can automatically detect the load state of the motor and develop a signal through the system to adjust the working-point voltage for enabling the triggering device of the principal circuit system to automatically adjust the firing angle so that the proper magnitude of the input voltage and current are effectively provided to the motor in accordance with its different load states.