A non-volatile semiconductor memory includes a word line extending in a first direction, a first electrode connected to the word line electrically, an ion diffusion layer with connected to the first electrode electrically, a second electrode connected to the ion diffusion layer electrically and formed of a metal to be diffused into the ion diffusion layer when a positive voltage is supplied thereto, and a bit line extending in a second direction perpendicular to the first direction, the bit line connected to the second electrode electrically. The ion diffusion layer has a first region disposed on the first electrode and a second region disposed between the first region and the second electrode, and the metal is more difficult to diffuse into the second region than into the first region.