There are provided a substrate for an inkjet head and an inkjet head wherein in a case where a protection layer of heating resistors is energized, an electrical connection with portions around the protection layer is more reliably cut. A first protection layer provided for the substrate for an inkjet head includes individual sections provided at positions corresponding to the plurality of heating resistors and a common section which commonly connects the plurality of individual sections. The individual sections and the common section are connected via connect sections which are eluted and connect in a case where an electrochemical reaction occurs between the connect sections and ink when electricity flow therethrough, so that an electrical connection between the individual sections and the common section is cut.