An annular magnet is formed by coupling a plurality of arc-shaped divided magnets with each other in an annular shape as well as such being magnetized with N and S magnetic poles on the end surfaces thereof in an axial direction, wherein the annular magnet is formed such that each of the divided magnets has joint portions at both ends thereof so that the divided magnets are joined to each other. Each of the joint portions also has a joint surface to overlap the joint portions of adjacent divided magnets in the axial direction. The joint surface is magnetized to a magnetic pole different from that of a joint surface to which such is joined, and the divided magnets are coupled with each other by the magnetic attraction force of different magnet poles.