A liquid ejection head includes a recording element substrate, a flow path member having a common supply flow path and a common collection flow path through which a liquid having a temperature higher than a temperature of the common supply flow path flows, and a support member supporting the flow path member. The common supply flow path and the common collection flow path are formed to extend along a longitudinal direction of the flow path member and be arranged side by side with each other in a lateral direction of the flow path member. The positions of the flow path member in the longitudinal direction and in the lateral direction are defined at a center portion in the longitudinal direction, and at a side surface located on the common supply flow path side in the lateral direction, among side surfaces extending in the longitudinal direction, respectively.