A process for producing an ink jet head comprising a liquid-discharge energy generating element for discharging a liquid, a discharge opening, a liquid-flow path, and a substrate for holding the liquid-discharge energy generating element, the process comprises the steps of: preparing the substrate; providing on the substrate the liquid-discharge energy generating element; providing a solid layer with a convex shape on the surface of the substrate where the liquid-discharge energy generating element has been provided and at the part where the liquid-flow path and the discharge opening are to be provided, the solid layer being formed of a resin capable of being dissolved away; applying on the substrate provided with the solid layer a curable material in a thickness larger than the thickness of the solid layer, to cover the solid layer; curing the curable material; evenly removing the cured material until the convex portion of the solid layer is laid bare; and dissolving away the solid layer to form the liquid-flow path and the discharge opening.