The present invention relates to a compound formula [I]: wherein ect., X is bond, —CH2—, etc., Y is bond, —O—(CH2)n— (in which n is 1, 2, 3 or 4), etc., Z is cyano, tetrazolyl, etc., R1 is hydrogen, lower alkyl, etc., R2 is hydrogen or an amino protective group, R3 is hydrogen or lower alkyl, R4 is hydrogen or lower alkyl, R5 and R8 are each independently hydrogen, halogen, hydroxy, lower alkyl, etc., R6 is hydrogen, lower alkyl, etc., R9 is hydrogen or lower alkyl, and i is 1 or 2, or a salt thereof. The compound [I] of the present invention and pharmaceutically acceptable salts thereof are useful for the prophylactic and/or the therapeutic treatment of pollakiurea or urinary incontinence.