The compound of the formula (I): wherein W is a group of the following formula (VIII) binding to any possible position on the Q: Q is, together with W, a group of the formula: —C(W)═C(R3A)—N(R3)—, etc.; R3A is H or optionally substituted lower alkyl; R4, R5, R6, and R7 are independently H or optionally substituted lower alkyl; R1 is optionally substituted lower alkyl, etc.; R2 is H, etc.; R3 is H, etc.; Ar is phenyl, etc., or a pharmaceutically acceptable salt thereof, where these compounds exhibiting β3-adrenoceptor-stimulating activity and being useful as a medicament for treatment of obesity, etc.