Aluminum alloy disc blank for magnetic disc and magnetic disc

An aluminum alloy disc blank for a magnetic disc made of an aluminum alloy comprising Fe:

• 0.005 to 1.800 mass %, Mn:
• 1.80 mass % or less, Cu:
• 1.00 mass % or less, Si:
• 14.00 mass % or less, Zn:
• 0.70 mass % or less, wherein Mn, Cu, Si, and Zn are present, with a balance being Al and inevitable impurities, and wherein the aluminum alloy disc blank for a magnetic disc has a flatness change when the aluminum alloy disc blank for a magnetic disc is held in the atmosphere at 50° C. or lower for 336 hours is 2.0 μm or less.