A substrate for an inkjet print head comprises: a base; a plurality of heating resistors for heating ink, the heating resistors being disposed on the base and producing heat in a case where the heating resistors are energized; a first protection layer disposed on the heating resistors and having insulation properties; and a second protection layer disposed on the first protection layer and having conductivity. The second protection layer includes individual sections disposed to individually cover the plurality of heating resistors, a common section connecting the individual sections, and connection sections interposed between the individual sections and the common section and connecting the individual sections and the common section. The connection sections are disposed at positions to be in contact with ink, and include a material which changes to an insulating film by an electrochemical reaction with the ink.