A liquid ejection head is provided with a recording element substrate, and the recording element substrate includes an ejection port member, an electric wiring layer including a pressure generating element array and electric connection portions, and a silicon substrate including the ejection port member and the electric wiring layer on a front surface. The silicon substrate includes a first through hole and a second through hole that protrude the electric connection portions. The rear surface of the silicon substrate is a (100) surface. An extension line of a side extending along the [110] direction, out of sides of the opening of the first trough hole and an extension line of a side extending along the [110] direction, out of sides of the opening of the second through hole are displaced from each other in a direction orthogonal to the [110] direction.