To elongate a service life by eliminating abrasion at a braking part, eliminate noise generated from the braking part, and achieve simplicity by structurally eliminating a movable part.

This electromagnetic brake for a motor 11 comprises an electromagnetic brake body 13 comprising yoke members 15a and 15b having an excitation coil winding 14, and a brake movable member 16 comprising a magnetic material disposed in a magnetic circuit formed by the electromagnetic brake body 13 through a gap 18, and fixed to a motor rotating shaft 2b. Magnetic fluid 20 is filled in the gap 18, and between the electromagnetic brake body 13 and the motor rotating shaft 2b, a seal member 19 to rotatably seal the motor rotating shaft 2b is disposed to prevent the leak of the magnetic fluid 20. When the excitation coil winding 14 is excited, the electromagnetic brake 11 makes braking action.