A plasma ion source includes: a gas introduction chamber, into which raw gas is introduced; an insulation member provided in the gas introduction chamber; a plasma generation chamber connected to the gas introduction chamber; a coil that is wound along an outer circumference of the plasma generation chamber and to which high-frequency power is applied; and an electrode arranged at a boundary between the gas introduction chamber and the plasma generation chamber and having a plurality of through-holes formed therein, wherein a size of the through-holes is smaller than a length of a plasma sheath.