Provided is a solvent for organic transistor production. The solvent has excellent solubility for organic semiconductor materials and enables formation of an organic transistor having high crystallinity. The solvent according to the present invention for organic transistor production includes a solvent A represented by Formula (a). In the formula, Ring Z represents a ring selected from an aromatic carbon ring, a 5- to 7-membered alicyclic carbon ring, and a 5- to 7-membered heterocyclic ring; R1 represents a group selected from oxo, thioxy, —ORa, —SRa, —O(C═O)Ra, —RbO(C═O)Ra, and substituted or unsubstituted amino; and R2 represents a group selected from hydrogen, C1-C7 alkyl, aryl, and —ORa, where R1 and R2 may be linked to each other to form a ring with one or more carbon atoms constituting Ring Z.