There is provided a magnetic field generator 10 which is capable of varying an orientation of a magnetic field at a target position P easily in all directions. The magnetic field generator 10 includes a pair of magnetic field generating units 16a, 16b which are disposed coaxially so that their respective first main surfaces 28a, 28b oppose in parallel to each other, with a gap G in between. The magnetic field generating units 16a, 16b are rotated by rotation drive units 20a, 20b respectively in Arrow A directions. By rotating each of the magnetic field generating units 16a, 16b in the same one direction of the Arrow A directions by the same angle, the orientation of the magnetic field at the target position P is varied on an X-Z plane. On the other hand, by rotating at least one of the magnetic field generating units 16a, 16b in an Arrow A direction so as to change positional relationship between the magnetic pole of the field generating unit 16a and the magnetic pole of the magnetic field generating unit 16b, the inclination of the orientation of the magnetic field at the target position P with respect to the X-Z plane is varied.