A method for manufacturing a glass substrate comprises a surface processing step of performing surface processing for forming unevenness on a glass surface. In the surface processing step, protruded portions having a height of 1nm or more from an average line of a roughness curve are dispersedly formed on the glass surface. In the surface processing step, the surface processing is performed such that a protruded portion area ratio is 0.5 to 10%. The protruded portion area ratio is a ratio of an area of the protruded portions with respect to an area of any rectangular region. The rectangular region has a square shape with a side length of 1 μm. In the surface processing step, in a case where the rectangular region is equally divided into at least one hundred divided regions having a square shape, the surface processing is performed such that a protruded portion content ratio is 80% or more. The protruded portion content ratio is a ratio of the number of divided regions having the protruded portions with respect to the number of divided regions included in the rectangular region.