The present invention relates to a method for manufacturing an ultra-thin glass substrate, the method including: a feeding step of feeding a preform for a glass substrate to a production line while being held; a heating step of heating the preform fed from the feeding step to a temperature around a softening point thereof; and a drawing step of drawing the preform that has softened in the heating step to form an ultra-thin glass substrate, in which the preform has been wound on a cylindrical first winding roll.