A manufacturing method for manufacturing a liquid ejection element substrate for a liquid ejection element for ejecting liquid through an ejection outlet, the liquid ejection element substrate including an energy generating element for generating energy for ejecting the liquid and an electrode for supplying electric power to the energy generating element, includes a step of forming on a front side of the substrate an energy generating element and wiring electrically connecting with the energy generating element; a step of forming a recess in the form of a groove on the side of the substrate at a position where the wiring is formed; a step of forming an embedded electrode electrically connected with the wiring by filling electrode material in the recess; and a step of thinning the substrate at a back side after formation of the embedded electrode to expose the embedded electrode at the back side of the substrate, thus providing an electrode exposed at the back side of the substrate.