A digital system for measurement of angular speed and acceleration or torque for motors is presented, which uses a usual flywheel method with a simple photo-sensor. In our system, an improved type of an inverse-time function generator is especially developed to obtain the accurate angular speed signal from the period of one revolution of the shaft. Despite of the simple form, this system has many advantage in measuring the wide speed range between 128 (or 12.8) and 32768 (or 3276.8) [r/min] with high accuracy of 3 (or 0.3) [r/min] and high acquisition rate (once a revolution). In addition to the digital output for the speed, the analog outputs for the speed and acceleration are also equipped for the torque-speed curve plotting of motors. As a practical application, the torque-speed curves of a two-phase servomotor and a hysteresis synchronous motor are measured.