Disclosed is a compound represented by the formula (I) below and a pharmaceutically acceptable salt thereof.This compound is useful for treatment of obesity, diabetes and the like. [In the formula (I), Ar represents a benzene ring or the like； X1 represents a nitrogen atom, a sulfur atom or the like； R1 represents an aryl group or the like； X2 represents a group represented by the following formula (II): (wherein R4 and R5 respectively represent a lower alkyl group or the like, and m represents a number of 2-4) or the like； one of X and Y represents an oxygen atom and the other represents a sulfanyl group or the like； and X3-X6 respectively represent —CH—, a nitrogen atom or the like.
