Abstract: The disclosed negative ion source uses a solid-state element having a semiconductor portion, which source includes a region adapted to dissociate molecules of hydrogen or deuterium in said solid-state element by dissolution, another region adapted to convert the atoms generated through the dissociation of said molecules into negative ions as said atoms reach the proximity of surface of said solid-state element through diffusion process by resonance transition of electrons in said solid-state element and to liberate the thus produced negative ions from said surface by hot electrons in said solid-state element, wherein the dissociation, electronic resonance transition, and liberation continuously occur in succession.