NON-MAGNETIC SUBSTRATE FOR MAGNETIC DISK, AND MAGNETIC DISK

A non-magnetic substrate for a magnetic disk (1) includes a substrate main body (3) having two opposing main surfaces (3a), the substrate main body (3) made of glass or aluminum alloy, and a metal film that is formed on the main surfaces (3a) and an outer circumferential edge surface of the substrate main body (3) and is made of a material having a loss factor of 0.01 or more. The non-magnetic substrate has a thickness (T+D) of 0.700 mm or less, the thickness (T+D) being the sum of a thickness T of the substrate main body (3) and a thickness D of the metal film, and a ratio D/T of the thickness D of the metal film to the thickness T of the substrate main body (3) is 0.025 or more. The outer circumferential edge surface of the substrate main body (3) forming an interface with the metal film has a surface roughness maximum height Rz of 0.5 ?m or more.