Abstract: Novel .alpha.-methyl-.beta.-aminopropiophenone derivatives having bronchodilator activity represented by the following general formula: ##STR1## where R represents alkyl having 1-6 carbon atom benzyl or phenyl; R.sub.1 and R.sub.2 individually represent alkyl having 1-6 carbon atom or they form, joining to each other together with the adjacent nitrogen atom with or without intervening an atom other than carbon atom, a saturated heterocyclic ring which may be substituted with lower alkyl; n is an integer of 0, 1 or 2 on the proviso that R represents methyl or ethyl if n is 0, as well as their non-toxic salts are presented. Method of producing the new derivatives and the bronchodilatation method using them are disclosed as well.