A manufacturing method of a solid-state imaging device includes: forming a first and second insulating films having different properties on a silicon substrate such that they cover sides of gate electrodes formed on the silicon substrate; subjecting the second insulating film to selective etching, and forming sidewalls on the sides of the gate electrode; subjecting the gate electrode having the sidewalls formed to ion implantation; covering the gate electrode having the sidewalls formed and forming a third insulating film on the silicon substrate; covering with a mask material part of the gate electrodes covered with the third insulating film, and subjecting the substrate to etching to remove exposed third insulating film; and, after removing the mask material, forming a metal film capable of forming a silicide on the silicon substrate such that the metal film covers the gate electrodes and the third insulating film to form a silicide layer.