A liquid ejection head is constituted by a liquid ejection substrate comprising a liquid supply port for supplying liquid, an ejection outlet for ejecting the liquid supplied from the liquid supply port, and ejection energy generating devices for generating energy for ejecting the liquid; and a supporting member having a supporting surface for supporting the liquid ejection substrate and a liquid supply hole for supplying liquid to the liquid ejection substrate, the liquid supply hole communicating with the liquid supply port of the liquid ejection substrate to form a communicating portion, a periphery of which is sealed by a sealant. The liquid supply hole of the supporting member has an opening larger than that of the liquid supply port of the liquid ejection substrate. The support member has an inner wall portion including an edge line portion defined by the liquid supply hole on a side where the liquid ejection substrate is to be disposed. The inner wall portion is covered with the sealant.