A nonvolatile semiconductor memory fabrication method including forming a first insulating film and a floating gate electrode material on a semiconductor substrate; forming a gate insulating film and a floating gate electrode by etching the first insulating film and the floating gate electrode material, respectively, and forming a groove for an element isolation region by etching the semiconductor substrate; and forming an element region and the element isolation region by burying a second insulating film in the groove and planarizing the second insulating film.