PURPOSE: To detect unusual operation at an early stage by means of a small number of temp. sensors by providing temp. sensors around the outer periphery of a rotor in an electromagnetic brake device and by interrupting power supplies to a motor and an electromagnetic brake.

CONSTITUTION: Temp. sensor 4a is mounted on a rod 8 for interconnecting a core 2 to an outer disk 5. When a shoe 3 is not completely opened due to any failure in the core 2, the poor operation of the shoe 3, or poor adjustment of gap g, a disk 4 keeps contact with the shoe 3 to generate heat at its contact part. A part of the shoe 3 may experience temp. rise. but since the disk 4 generates heat on its whole area, the resulting heat causes the temp. sensor 4a to detect temp. rise in the disk 4 so as to suspend electrification of an electromagnetic brake as well as of a motor. The above constitution can detect unusual temp. rise in the disk 4 or the shoe 3 by only providing a small number temp. sensors 4a.