A method of manufacturing a liquid ejection head includes a step of forming a layer of a positive-type photosensitive resin on a substrate; a step of forming a pattern, used to form a liquid channel, by exposing the positive-type photosensitive resin layer to light; a step of forming a photosensitive layer, used to form a discharge port-forming member, on the pattern; and a step of forming a discharge port in such a manner that the photosensitive layer is patterned by exposing the photosensitive layer to i-line. The pattern has a predetermined absorbance for i-line and contains a specific compound.