A method of manufacturing an organic thin film transistor , the method comprising: a transistor forming step of forming a transistor element on a first gas barrier layer of a transfer type gas barrier film including a substrate and the first gas barrier layer , the transistor element including a gate electrode , an insulating film , an organic semiconductor layer , a source electrode , and a drain electrode , the first gas barrier layer including a resin layer and an inorganic layer , the resin layer being peelable from the substrate , and the inorganic layer being formed on the resin layer ; a bonding step of bonding a transfer type gas barrier film including a substrate and a second gas barrier layer to the transistor element through an adhesive layer , the second gas barrier layer including a resin layer and an inorganic layer , the resin layer being peelable from the substrate , the inorganic layer being formed on the resin layer , and the transfer type gas barrier film being bonded such that the inorganic layer side faces the transistor element ; and a peeling step of peeling the substrate from each of the two transfer type gas barrier films , wherein in the bonding step, the transfer type gas barrier film is bonded such that at least one of a thickness (T1, T2) of the resin layer in the first gas barrier layer or a thickness of the resin layer in the second gas barrier layer is less than a thickness (T0) ranging from a surface of the inorganic layer of the first gas barrier layer on a side opposite to the resin layer _to a surface of the inorganic layer of the second gas barrier layer on a side opposite to the resin layer . a transistor forming step of forming a transistor element on a first gas barrier layer of a transfer type gas barrier film including a substrate and the first gas barrier layer , the transistor element including a gate electrode , an insulating film , an organic semiconductor layer , a source electrode , and a drain electrode , the first gas barrier layer including a resin layer and an inorganic layer , the resin layer being peelable from the substrate , and the inorganic layer being formed on the resin layer ; a bonding step of bonding a transfer type gas barrier film including a substrate and a second gas barrier layer to the transistor element through an adhesive layer , the second gas barrier layer including a resin layer and an inorganic layer , the resin layer being peelable from the substrate , the inorganic layer being formed on the resin layer , and the transfer type gas barrier film being bonded such that the inorganic layer side faces the transistor element ; and a peeling step of peeling the substrate from each of the two transfer type gas barrier films , wherein in the bonding step, the transfer type gas barrier film is bonded such that at least one of a thickness (T1, T2) of the resin layer in the first gas barrier layer or a thickness of the resin layer in the second gas barrier layer is less than a thickness (T0) ranging from a surface of the inorganic layer of the first gas barrier layer on a side opposite to the resin layer _to a surface of the inorganic layer of the second gas barrier layer on a side opposite to the resin layer . <EOS>