The present invention is aimed to provide a method for producing a glass substrate with a thickness of not more than 200 μm, which is satisfied with the quality required for a substrate on which a thin-film electric circuit is formed, and a sheet glass substrate obtained according to this method. The present invention is concerned with a method for producing a glass substrate having a sheet thickness of from 10 to 200 μm, including a forming step of forming a molten glass into a ribbon shape in accordance with a down draw method, an annealing step of annealing the glass ribbon, and a cutting step of cutting the glass ribbon to give a glass substrate, wherein an average cooling rate in a temperature range of from the (annealing point+200° C.) to the (annealing point+50° C.) is controlled to the range of from 300 to 2,500° C./min.