A method of manufacturing a semiconductor device having an organic semiconductor film comprises a step of preparing a transparent substrate at least having an opaque gate electrode and a gate insulator thereover, a step of forming a layer containing metal-nano-particles as a conductive layer for a source electrode and a drain electrode to the thus prepared transparent substrate, a step of applying exposure to the transparent substrate on the side of a surface not mounted with the opaque gate electrode, a step of flushing away a portion other than the source electrode and the drain electrode in the layer containing the metal-nano-particles after the exposure, and a step of forming an organic semiconductor layer forming a channel portion. Lower and upper electrodes are positioned in self-alignment manner and thus no positional displacement occurs even if a printing method is used. Accordingly, semiconductor devices such as flexible substrates using an organic semiconductor can be manufactured inexpensively by using a printing method.