Abstract: The object of the present invention is to provide an agent for promoting IFN-? production, which can be safely applied to living bodies; the present invention solves the problem by providing an agent for promoting IFN-? production, which comprises a tri-heterocyclic polymethine cyanine dye(s), and a method for producing IFN-?, which comprises a step of allowing the agent to act on immunocompetent cells.