Abstract: A kinetofrictional force testing apparatus has a spindle rotated by a variable speed motor. A load cell is disposed in opposition to a disk coupled to the spindle and includes a test head for the disk, a rotational frequency controlling synthesizer, and a personal computer for general control. The rotational speed of the motor is varied on the basis of clock pulses from the rotational frequency controlling synthesizer associated with the personal computer. The rotational frequency and rotational acceleration/deceleration of the disk coupled to the spindle are digitally controlled by a predetermined program set in the personal computer. The test head is supported by a leaf spring having strain gauges mounted on its lateral surfaces. Frictional forces are measured by the output of the strain gauges.