A base member for use in manufacturing an ink jet recording head, which includes a supply port, an ejection outlet, a liquid flow path for directing liquid supplied from the supply port to the ejection outlet, and an ejection pressure generating element, disposed in the liquid flow path, for ejecting the liquid. The supply port is formed as a through-opening in a substrate on which the ejection pressure generation element is provided. The base member includes a recessed portion formed on the side of the substrate provided with the ejection pressure generation element. The recessed portion extends from an edge of the supply port to a neighborhood of the ejection pressure generation element. A protection layer is provided at least on a portion of the substrate surface constituting the recessed portion.