A magnetic circuit, provided with a short magnet (1a) and short magnet (1b) that are arranged in an array, and a yoke (2a) and a yoke (2b) provided so as to sandwich the short magnet (1a) and short magnet (1b). The short magnet (1a) and short magnet (1b), are arranged, that have a space between them that is a predetermined gap (3) or less in the arrangement direction of the array respectively. In addition, the short magnet (1a) and short magnet (1b) are arranged so that one magnetic pole is located on the side toward one of the pair of yokes (2a) and (2b), and the other magnetic pole is located on the side toward the other yoke.