A method for forming an organic semiconductor film includes: forming a solution film by applying a solution containing an organic semiconductor material and a solvent to at least a part of a substrate; and drying the solution film by irradiating at least a part of the solution film with electromagnetic waves with a wavelength of at least 8 μm and an energy density of from 0.1 to 10 J/cm2 on the surface of the solution film before the solution film dries. An organic semiconductor film having good crystallinity can be formed by the method.