A focusing unit (1) comprises a linear motor driven in two phases, and comprises a two-phase coil (10a, 10b) and a drive magnet (9) that is disposed along the drive direction at a position opposite the two-phase coil (10a, 10b). The winding width of the coils (10a, 10b) in the portion opposite the drive magnet (9) is within an electrical angle range of 120°±7.7°, the average width of the coil at the portion opposite the drive magnet (9) is within an electrical angle range of 144°±4.6°, and the pitch between the two phases of coil (10a, 10b) is an electrical angle of 90°+180°×n (n is an integer of 0 or more).