A liquid ejection head chip includes a liquid ejection unit having a plurality of ejection orifices for ejecting a liquid, a flow path in communication with the ejection orifices, and an energy generating element that generates energy for ejecting the liquid, the liquid ejection unit being provided on an upper surface formed of a (100) surface of a silicon single-crystal substrate. The side surfaces in at least one of two combinations of opposing side surfaces of the substrate have (111) surfaces of silicon single crystal and the angles of the (111) surfaces relative to the (100) surface are supplementary to each other.