A liquid ejection head is constructed by providing a recording element substrate on a supporting member. The recording element substrate has at least one thermal energy generating element and a liquid supply port for supplying liquid to the element. The supporting member has three or more supply flow paths running therethrough. Two or more beams are formed in each of the supply flow paths. The gap between the beams formed in each of the end supply flow paths is greater than the gap between the beams formed in an inside supply from path.