It is intended to provide a compound useful as a drug which has an effect of inhibiting the binding of S1P to its receptor Edg-1(S1P1). A compound represented by the following formula (I): [Chemical formula 1] wherein Ar represents a monocyclic heterocycle having 1 or 2 nitrogen atoms; A represents oxygen, etc.; Y<1>, Y<2> and Y<3> independently represent each carbon or nitrogen; R<1> represents hydrogen, C1-6 alkyl, etc.; R<2> represents C1-6 alkyl, C3-8 cycloalkyl, etc.; R<3> represents C1-18 alkyl, etc.; R<4 >represents hydrogen or C1-6 alkyl; and R<5> represents C1-10 alkyl, etc.; or a pharmaceutically acceptable salt thereof.