PURPOSE: To permit several intermagnetic pole distances to be set in one unit of apparatus by permitting at least one of the upper and lower pole pieces to be moved vertically.

CONSTITUTION: When a sample is inserted between the magnetic poles of an objective lens, the interval between pole pieces is widened by transferring the inner cylinder 33 of the lower side magnetic pole downward, and after a sample stage 23 is inserted, the inner cylinder 33 of the lower side magnetic pole is transferred upward, and the head part of the inner cylinder 33 of the lower side magnetic pole is inserted into the recess part 55 on the sample stage 23, and the magnetic piece is brought to the position close to a sample 53. Accordingly, the interval between magnetic poles can be reduced when the sample is observed. Vertical operation of the magnetic pole is permitted on the upper side pole piece 7, and thus the objective lens which possess ultra-high resolving power can be obtained.