Disclosed is a novel arylalkylamine derivative represented by the formula (I) ##STR1## wherein X represents --O--, --CH.sub.2 -- or --NR.sup.3 -- in which R.sup.3 represents hydrogen or lower alkyl; Y represents --NH-- or ##STR2## Z represents ##STR3## in which R.sup.4 represents hydrogen or lower alkyl or ##STR4## Q represents an optionally substituted aryl or optionally substituted aromatic heterocyclic group; each of R.sup.1 and R.sup.2 independently represents hydrogen or lower alkyl; each of m and n independently represents an integer of 0 or 1; and a pharmaceutically acceptable salt thereof. The compound (I) and a pharmaceutically acceptable salt thereof show bronchodilatory and antiallergic activities, and are useful for treating respiratory disorders such as bronchial asthma.