Provided is an aluminum alloy substrate for a magnetic disk that includes an aluminum alloy containing 0.4 to 3.0 mass % (hereinafter abbreviated as “%”) of Fe, 0.005% to 1.000% of Cu, and 0.005% to 1.000% of Zn, with a balance of Al and unavoidable impurities. This substrate has a ratio A/B of 0.70 or more, where A indicates a distribution density of Al—Fe intermetallic compound particles having maximum diameters of 10 μm or more and less than 16 μm, and B indicates a distribution density of Al—Fe intermetallic compound particles having maximum diameters of 10 μm or more. The distribution density of Al—Fe intermetallic compound particles having maximum diameters of 40 μm or more is at most one per square millimeter. Also provided are a method of fabricating this aluminum alloy substrate for a magnetic disk and a magnetic disk composed of the aluminum alloy substrate for a magnetic disk.