PROVIDED ARE COMPOUNDS HAVING AN EXCELLENT HYPOGLYCEMIC ACTION AND A β CELL- OR PANCREAS-PROTECTING ACTION OR A PHARMACEUTICALLY ACCEPTABLE SALT THEREOF, AND A PHARMACEUTICAL COMPOSITION HAVING AN EXCELLENT THERAPEUTIC EFFECT AND/OR PROPHYLACTIC EFFECT ON TYPE 1 DIABETES, TYPE 2 DIABETES, AND THE LIKE, WHICH CAUSE AN INCREASE IN THE BLOOD SUGAR LEVEL DUE TO ABNORMAL SUGAR METABOLISM. A COMPOUND REPRESENTED BY GENERAL FORMULA (I), OR A PHARMACEUTICALLY ACCEPTABLE SALT THEREOF, IS DISCLOSED.