Abstract: Provision of a superior URAT1 activity inhibitor effective for the treatment and the like of a pathology involving uric acid, such as hyperuricemia, gouty tophus, acute gouty arthritis, chronic gouty arthritis, gouty kidney, urinary lithiasis, renal dysfunction, coronary heart disease, ischemic cardiac diseases and the like. A URAT1 activity inhibitor containing a compound represented by the following formula [1] or a pharmaceutically acceptable salt thereof, or a solvate thereof as an active ingredient: wherein each symbol is as defined in the specification.