Abstract: The present invention provides to intractable skin diseases such as athlete's foot a substance which has a percutaneous absorption promoting effect capable of enhancing the effectiveness of an antifungal agent, etc., and is high in safety to skin which becomes sensitive to irritation because of the diseases. Coenzyme Q, which is known to be highly safe in oral administration, was found to have high safety to skin and a percutaneous absorption promoting effect to an antifungal agent. From this, a useful composition composed of coenzyme Q and an antifungal agent can be provided to athlete's foot which is difficult to be completely cured.