Provided is an ink that is the most suitable for a method for forming an organic transistor by transferring a pattern using a liquid-repellent transfer substrate, for example, a microcontact printing method or a reverse printing method. Specifically, provided is an organic semiconductor ink composition which can provide a uniform ink coating film on a surface of a liquid-repellent transfer substrate and which can provide a dry ink film or a semi-dry ink film capable of being easily transferred from the transfer substrate to a transfer-receiving base material. Also provided is a method for forming an organic semiconductor pattern of an organic transistor, the method using the organic semiconductor ink composition. The organic semiconductor ink composition used for obtaining a desired pattern by transferring an ink layer formed on a liquid-repellent transfer substrate to a printing base material contains an organic semiconductor, an organic solvent, and a fluorine-based surfactant.