A method of manufacturing a substrate for a liquid discharge head having a supply port passing through a silicon substrate provided with an energy-generating element generating the energy used to discharge a liquid and allowing liquid to be supplied to the energy-generating element, includes preparing a silicon substrate in which a first etching mask having a first opening is provided on a first face, and a second etching mask having a second opening is provided on a second face that is the rear face of the first face; forming a first recess towards the second face from the first face within the first opening, and forming a second recess towards the first face from the second face within in the second opening; and performing crystalline anisotropic etching using the first and second etching masks as masks from both of the first and second faces, to form the supply port.