THIAZOLIDINEDIONE COMPOUND

PROBLEM TO BE SOLVED: To provide a compound useful as a medicine, in particular as an insulin secretion promoter and a prophylactic and/or therapeutic agent for diseases associated with GPR40 such as diabetes.SOLUTION: The invention is accomplished based on a finding resulting from study on a compound having a GPR40 receptor agonist action, that a thiazolidinedione compound including thiazolidinedione binding to a 6-membered monocyclic aromatic ring via a carbon atom with the aromatic ring further binding to benzene substituted with a 6-membered monocyclic aromatic ring via a linker, and a salt thereof exhibit excellent GPR40 agonist activity. The thiazolidinedione compound can be used as an insulin secretion promoter, and a prophylactic and/or therapeutic agent for diabetes.