The present invention provides a substrate for ink jet including a heating resistor generating thermal energy for discharging an ink from an ink discharge port and an upper protective layer which is formed above the heating resistor and has a contacting surface with the ink. Furthermore, the upper protective layer is made of an amorphous alloy consisting of Ta and Cr in which the content of Ta is more than that of Cr. This constitution allows for the substrate excellent in cavitation resistance and corrosion resistance, and capable of high durability while having similar discharge performance to that of a conventional protective layer made of a Ta film. The present invention further provides an ink jet head comprising the above-mentioned substrate, and a manufacturing method thereof.