A glass substrate obtained by a method including measuring flatness of a glass substrate surface and measuring concentration distribution of dopant in the substrate. Processing conditions of the surface are set up for each site of the substrate based on results from the measuring the flatness and the measuring the distribution, and the finishing is carried out while keeping an angle formed by normal line of the substrate and incident beam onto the surface at from 30 to 89°. The surface is subjected to second finishing for improving an RMS in a high spatial frequency region. The surface after the second finishing satisfies the requirements: an RMS slope in the region that 5 μm