A fuel injector includes an injection-port forming member, a passage forming member, and a positioning member. The passage forming member is in contact with the injection-port forming member. The positioning member that is a partially ring shape spans and is externally fitted to the injection-port forming member and the passage forming member, and executes a positioning between the injection-port forming member and the passage forming member. The injection-port forming member and the passage forming member include continuous flat surfaces that can be connected with each other, respectively. The positioning member includes an opposite flat surface that faces both the continuous flat surfaces in a case where the positioning member is externally fitted to the injection-port forming member and the passage forming member, and a pressing portion that inwardly presses the outer peripheral wall portions such that the continuous flat surfaces are in contact with the opposite flat surface.