To respond to inspection of various timepiece movements by having a magnetism detection means for detecting magnetism generated from the rotor of a motor and a polarity detection means for detecting the polarity of the magnetic pole of the rotor and outputting a polarity signal in response to the polarity.

When a rotor R incorporated to timepiece movement M is rotated, change of a magnetic sensor 1 of the rotor R is detected by setting a probe 1a of the magnetic sensor 1 in the outside of the movement M. When the movement is normally operated, a detection signal S detected by the sensor is changed in the form of a sine wave with rotation of the rotor R. The detection signal S is output to a polarity detection circuit 2. When the signal S from the sensor 1 is sampled with a circuit 2, intervals are performed two times at intervals of 50m sec. This detects a pulse-like signal and prevents erroneous discrimination with a discriminator. It is judged whether the rotor normally rotates or not on the basis of a polarity signal POLE and another polarity signal STS in the device 3.