Method of manufacturing structure and method of manufacturing liquid ejection head

A method of manufacturing a liquid ejection head, the liquid ejection head including a channel member in which an ejection orifice from which a liquid is ejected and a channel that communicates with the ejection orifice are provided, the channel member including an ejection orifice member in which the ejection orifice is provided and a channel sidewall member that provides sidewalls of the channel;

• and a substrate having a supply port from which the liquid is supplied into the channel, the method comprising:
• (1) positioning a first resin layer, which is made of a dry film and to be the channel sidewall member, provided on a first supporting member on a substrate having a through hole while heating and pressurizing the first resin layer, with the first resin layer facing toward the substrate, and releasing the first supporting member from the first resin layer;
• and
• (2) positioning a second resin layer, which is to be the ejection orifice member, provided on a second supporting member on the first resin layer from which the first supporting member has been released, with the second resin layer facing toward the first resin layer, and releasing the second supporting member from the second resin layer,
• wherein a first resin layer portion that is above the through hole is removed simultaneously with the releasing of the first supporting member with the first resin layer portion being stuck to the first supporting member, and
• wherein a thickness of the first resin layer is 8 μm or smaller.