[Problem to be Solved]A method for producing a flexible glass substrate which is approximately 100% impermeable to gas or vapor and excellent in bendability and a flexible glass substrate are provided.[Solution]After forming of a pattern P on a surface of a glass substrate 1, a support 3 is temporarily attached to the surface, the glass substrate 1 is thinned by etching another surface of the glass substrate 1, a film base 5 is laminated to the etched another surface, and the temporarily attached support 3 is peeled off from the one surface of the glass substrate 1.