Liquid ejection head

A liquid ejection head configured to eject a liquid from an ejection port by applying energy to the liquid from an energy generation element, wherein

• the ejection port includes an opening portion having a longitudinal direction and a transverse direction,
• the opening portion includes a protrusion, first regions, and a second region,
• the protrusion is arranged in each of facing positions of the ejection port in the longitudinal direction,
• the first regions are regions excluding the protrusions of the ejection port and are regions of the opening portion that are along the longitudinal direction and partitioned by the protrusions,
• the second region is a region excluding the protrusions of the ejection port and is a region of the opening portion that bridges the first regions between the facing protrusions, and
• the following formulae (A) and (B) are satisfied:
• M
• /
• L
• >
• 1.
• ;
• (
• A
• )
• (
• L
• -
• a
• )
• /
• 2
• ⁢
• L
• <
• 0.4
• ,
• (
• B
• )
• where
• the maximum length in the longitudinal direction is M, the maximum length in the transverse direction is L, and a half width of the protrusion is a.