The present invention is a method for manufacturing an organic thin-film transistor substrate including an organic thin-film transistor as a transistor element, and an object of the invention is to provide a manufacturing method capable of forming a bank in a smaller number of steps. The method for manufacturing the organic thin-film transistor substrate of the present invention, in which an organic thin-film transistor is formed in a first region on a substrate, a second region for forming a light-emitting element in abutment with the first region is included, and a bank part is formed in a peripheral part of the second region, is characterized by including: a first step of forming the organic thin-film transistor in the first region on the substrate and forming at least one of the gate insulation layer and the organic semiconductor layer included by this organic thin-film transistor as far as the second region, thereby forming, in the second region, a bank precursor layer composed of a laminated structure formed on the second region; and a second step of removing the regions of the bank precursor layer other than the peripheral part, thereby forming the bank part made of the remaining bank precursor layer.