A magnetic circuit that forms an arc-shaped magnetic field space is provided. Of two magnets constituting a first magnetic circuit 10, a first magnetic pole 1 is provided with a first yoke 11 that is arc-shaped in planar view, a first magnet 13 that is arc-shaped in planar view and a magnetic pole piece 15. On the other hand, a second magnetic pole 2 is provided with a second yoke 21 that is arc-shaped in planar view, a second magnet 23 that is arc-shaped in planar view and a magnetic pole piece 25. The first magnetic pole piece 15 and the second magnetic pole piece 25 are disposed so as to be opposed to each other while being separated from each other. The first magnet 13 and the second magnet 23 are formed by arranging a plurality of small magnets.
