To improve tolerance dose of electrostatic discharge of a substrate for a recording head of an inkjet print head, and to prevent also erroneous operation from occurring when the discharge is generated.

A plurality of polycrystalline silicon films used as an input protective resistance are arranged as a straight line layout and they are connected with each other in series with a metal wiring. As there is no possibility of generating a concentrated part of electric current in comparison with a conventional curved layout, it is expected to improve electrostatic withstand voltage. In addition, at the same time, a well layer of impurities different from the type of impurities of the substrate is formed on a silicon substrate on the lower part of the polycrystalline silicon film. It is expected thereby to improve insulation withstand voltage by adding a joining capacity and to prevent communication to substrate electric potential when dielectric breakdown occurs.

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