The present invention relates to an alkali-free glass substrate, having a strain point of 680° C. or higher, a Young's modulus of 78 GPa or greater, an UV transmittance at a wavelength of 300 nm of from 40% to 85% in terms of 0.5 mm thickness, an in-plane distribution of the UV transmittance at a wavelength of 300 nm in a G6-sized substrate of 1% or less in terms of 0.5 mm thickness, an average cooling rate around the glass transition point obtained according to a rate cooling method of 400° C./min or lower, and an in-plane distribution of the average cooling rate of 40° C./min or less.