PURPOSE: To reduce the size of the whole equipment and facilitate its manufacture by fixing one terminal of a silicon thin plate to a support base, and fitting a rotating body to be measured to the other terminal of the silicon thin piece detachably.

CONSTITUTION: One terminal of the silicon thin piece 2 is fixed to the support base 4, and the rotating body to be measured is fitted to the other terminal of the silicon thin piece 2 detachably. On the other hand, a fitting means 8 for a stepping motor is provided to the terminal part of the silicon thin piece 2. Then, an output shaft 9 is fitted so that its center line is aligned to that of the silicon thin piece 2. A diffused resistance is formed directly on the silicon thin piece 2. Therefore, the thin piece is reduced in width and the shape of the whole equipment is reduced in size. Further, the diffused resistance 3 is formed by semiconductor technique, so it is formed extremely easily.