PROBLEM TO BE SOLVED: To provide a liquid ejection head excellent in electrical reliability. A liquid ejection head includes a recording element substrate (2) and an electrical wiring substrate (302) held by an electrically insulating substrate (301), and leads (302b) protruding from an edge of the substrate. 3 and. The leads 302b and the recording element substrate 2 are electrically connected. The electrical connection portion between the lead and the recording element substrate and the lead are sealed by the first sealing material 50. The lead has at least one of a concave portion 309 and a convex portion provided on the surface of the lead in a region between the root portion and the tip portion, and the concave portion and the convex portion of the lead surface from the root portion. Of the parts reaching at least one of the parts, at least the root part is covered with the second sealing material 5. [Selection diagram] Figure 8
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