This invention relates to compounds which are represented by the general formula [I] [in which A stands for a group of the following formula [a0] or [b0] Ar1, Ar2 and Ar3 stand for optionally substituted phenyl; k stands for 0 or 1; m, n and a stand for 0, 1 or 2; R1 stands for hydrogen or optionally substituted lower alkyl; R2, R3, R4 and R5 either stand for hydrogen or optionally substituted lower alkyl, or R2 and R3, or R4 and R5 together stand for trimethylene and the like; R60 stands for hydrogen, alkyl, or the like; R61 and R71 either stand for alkyl and the like, or together stand for trimethylene and the like; X stands for carbonyl or methylene; Y stands for nitrogen or methine; and Q− stands for anion], and the like. The compounds of the invention exhibit selective antagonism to muscarinic M3 receptors, and therefore are useful as safe and effective agents showing little side effect, for treating diseases of the respiratory, urinary and digestive systems.