To miniaturize an electromagnetic brake 14 while braking is enhanced.

A pair of iron cores 28 where both end surfaces in length direction, which are to be pole surfaces, face armatures 18 is provided between the pair of armatures 18. An excitation coil 33 is so wound around the iron core 28 that the magnetic poles of both iron surfaces 28 are opposite to each other. Thus, almost magnetic flux passes the pole surface of the iron core 28, and leaking of magnetic flux from the parts other than pole surfaces is strongly limited. So, the attracting force of an electromagnet 34 is increased without increasing the electrification power and the number of turns of the excitation coil 33.