A liquid ejection head manufacturing method includes, in the following order, preparing a substrate having a flow path mold; arranging a first layer serving as a flow path wall member so as to cover the flow path mold; curing a portion of the first layer serving as a flow path sidewall; arranging a second layer so as to cover the cured portion of the first layer and the flow path mold; planarizing the second layer by pressing the second layer toward the substrate; arranging the ejection port in the first layer and the second layer; and forming the flow path by removing the flow path mold.