It is a technical challenge to provide a small-sized ion source excellent in operability. An ion source of the present invention includes: a cylindrical insulation tube (2) opened upward and opened at part of its lower surface
a plurality of hollow cylindrical permanent magnets (3), provided on the outer peripheral surface of the insulation tube to be arranged in a row in the axial direction of the insulation tube
a gas supplying means (34, 35, 20) for supplying gas into the insulation tube
a cathode electrode, at the tip end of which a fitting unit (19) for fitting of a solid material (18) there to is formed
an annular anode electrode (5), which is fitted to an opening in the lower surface of the insulation tube
an upper frame (6), which blocks the upper portion of the insulation tube and suspends the cathode electrode so as to allow the fitting unit to approach the anode electrode
and a lower frame (7), in which an extraction port (37) is formed for extracting ions emitted from the anode electrode, and on which the insulation tube is mounted.