A heat generating resistor comprised of a film composed of a TaN0.8-containing tantalum nitride material which is hardly deteriorated and is hardly varied in terms of the resistance value even upon continuous application of a relatively large quantity of an electric power thereto over a long period of time. A substrate for a liquid jet head comprising a support member and an electrothermal converting body disposed above said support member, said electrothermal converting body including a heat generating resistor layer capable of generating a thermal energy and electrodes being electrically connected to said heat generating resistor layer, said electrodes being capable of supplying an electric signal for demanding to generate said thermal energy to said heat generating resistor layer, characterized in that said heat generating resistor layer comprises a film composed of a TaN0.8-containing tantalum nitride material. A liquid jet head provided with said substrate for a liquid jet head. A liquid jet apparatus provided with said liquid jet head.