PURPOSE: To obtain a magnetic field adjuster which allows shorter mounting work time while eliminates the formation of a circulation loop of an induction current when a pulse magnetic field generation coil is driven in the apparatus which uniformizes a magnetic field using a circular magnetic body.

CONSTITUTION: An roughly cylindrical coil 1 for generating a magnetostatic field and a non-magnetic cylinder 9 to be inserted almost concentrically into the coil 1 are arranged and a thin belt-shaped magnetic body 10 having a width necessary for the correction of an uneven magnetic field is wound on the non- magnetic cylinder 9 by a necessary thickness to form a magnetic field adjustor.