A new electronic controller for continuously varying the speed of windshield wiper motor has been developed. It permits conventional wiper motors without any modification to be set at any speed, low to high, for sophisticated wiper operation.Speed control is based on PWM and power MOS FETs. Fundamental problems peculiar to this method such as audible noise generation, R.F. noise generation, starting torque reduction, and speed drift due to load variation have been solved. Further, provided with the controller, the motor can keep its preset speed constant against changes in voltage, temperature, and torque. The controller, packaged in a small unit, is available at a low cost, and durable under severe automotive environment.