PURPOSE: To provide a device for detecting a rotation of a stepping motor by an induced voltage signal to be induced in a detecting winding without using a separate external sensor as a rotation detector for speed.position, etc.

CONSTITUTION: Detecting windings (a), (b) are provided at windings A, B of stator main windings A, A', B, B' of a stepping motor 2, and induced voltages E2a, and E2b are input to a rotation detector 1. The detector 1 has an output amplifier 3, a signal processor 4 for removing noise, a subtracter 5 for removing unnecessary voltage component by using output voltages E8A, E8A', E8B, E8B' from a magnetic coupling winding 8 with a main winding circuit, a waveform shaper 6 for converting to a signal to be digitized, and a diagnosing circuit 7 for deciding whether the motor is normally rotated or not.