Provided is a method for manufacturing a substrate for liquid ejection head including an ejection energy generating element and a nozzle layer including an ejection port and a liquid channel. The method includes the steps of: forming, on the substrate including the element, a metal mold member made of metal and having a flat surface, the metal mold member making up at least a part of a mold for the liquid channel, and a planarization layer made of the metal and having a flat surface to planarize a surface of the nozzle layer; coating the mold for the liquid channel and the planarization layer with negative-type photosensitive resin, thus forming a negative-type photosensitive resin layer to be the nozzle layer; exposing the resin layer to ultraviolet rays, thus forming the ejection port; and selectively removing the mold for the liquid channel, thus forming the liquid channel.