A coil unit includes first and second coils that are apposed, and third and fourth coils located on the rear side of the first and second coils so as to interpose the center of the first coil and the center of the second coil between the third and fourth coils, in the direction of alignment of the first and second coils. The axial direction of the third and fourth coils is substantially perpendicular to the axial direction of the first and second coils. First to fourth drive control units control the directions or phases of the currents to be supplied to the first to fourth coils, respectively.