In an electromagnetic fuel injection which is structured such that both end surfaces of an inner circumferential iron core portion and an outer circumferential iron core portion face a movable iron core, and a non-magnetic portion made of a metal material is provided between both end surfaces, an object of the present invention is to realize a structure of the electromagnetic fuel injector in which a surface of a target object is unlikely to be affected by a heat treatment with the surface facing the movable iron core. In an electromagnetic fuel injector 1 of the present invention which is structured such that both end surfaces of an inner circumferential iron core portion 401a and an outer circumferential iron core portion 401b face a movable iron core 402, and a non-magnetic portion 401d made of a metal material is provided between both end surfaces, in order to achieve this object, heat in a target member to be heat treated is generated by applying energy to a target member's surface which is different from a target member's surface that faces the movable iron core 402. More preferably, energy is applied to a surface different from a surface on a side that faces the movable iron core 402.