The present invention to provide a novel pyruvate dehydrogenase kinase inhibitors. A pyruvate dehydrogenase kinase inhibitor comprising a compound represented by the general formula (I) as an active ingredient (wherein, ring A represents a 6-membered aromatic hydrocarbon ring optionally substituted with 2-4 substituents,R1 and R4, which are the same or different, represent a hydrogen atom, a hydroxyl group, an optionally substituted C1-6 alkyl group, R2 and R3, which are the same or different, represent a hydrogen atom, a carboxyl group, an optionally substituted C1-6 alkyl group, an optionally substituted C6-10 aryl group, or a group represented by —C (═R9)—R10), a pharmaceutical composition for treatment or prophylaxis of diseases or disorders that pyruvate dehydrogenase kinase relates to its development or aggravation, and a cosmetic composition, and the like.
