A preparing method for a substrate for a stamper where the entirety of the metal rolled plate can be used as the material for the substrate so that a high yield in the preparation can be maintained is provided. A metal is rolled so as to generate a metal rolled plate, the metal rolled plate that is generated is cut to a predetermined size, and metal plating is operated on the front surface or the rear surface, or both the front and rear surfaces, of the metal rolled plate that has been cut to a predetermined size, and then, a polishing process is operated. A target plate thickness that is set when the metal rolled plate is rolled is smaller than the plate thickness that is required at the time of completion of the polishing process.