Process for producing liquid ejection head and liquid ejection head

A process, which produces a liquid ejection head including a recording element substrate having a principal surface and a support member having a color separation wall for ink flow paths and an outer wall, the substrate being narrower than the support member, a plane formed by conducting translation of a lower side of a substrate outer surface perpendicularly to the principal surface having an intersection with an outer wall top surface at a position distant from an inner edge of the outer wall top surface by an outward distance, includes applying an adhesive onto top surfaces of the outer and color separation walls such that a surface height of the adhesive at the intersection is higher than that at a position distant from an inner edge of the color separation wall top surface by the outward distance, and bonding and fixing the substrate to the support member with the adhesive.