A method for producing a substrate for an ink jet recording head comprises preparing a substrate with plural heat generating resistors for applying heat to the ink, plural wirings electrically connected thereto, and plural heat generating areas formed by the heat generating resistors exposed from the wirings, coating the heat generating resistors and the wirings on the substrate with a first insulating protective film, removing the first insulating protective film by wet etching in portions on the heat generating areas, and coating thus etched first insulating protective film with a second insulating protective film, wherein the etched portion of the first insulating protective film, in the longitudinal direction of the heat generating area, is positioned inside from the end of the heat generating area, by at least 1/2 of the thickness of the first and second insulating protective films covering the wirings.The protective film is thus made thinner on the heat generating areas, thus reducing the electric power consumption while maintaining sufficient durability.