A manufacturing method of a liquid ejection head includes forming on a substrate a first flow passage wall forming member contacting a solid layer of equal height, exposing a first layer of a negative photosensitive resin material to form an ejection outlet forming member; exposing a second layer, on the first layer, of a negative photosensitive resin material to form a second flow passage wall forming member for forming another part of the wall of the flow passage; placing the exposed first and second layers on the solid layer and the first flow passage wall forming member so that a non-exposed portion of the second layer contacts the solid layer; forming parts of the flow passage and the ejection outlet by removing non-exposed portions of the first and second layers above the substrate; and forming the flow passage by removing the solid layer.