Phenylethanolamine compounds represented by general formula (I) and pharmacologically acceptable salts thereof which have a potent effect of stimulating β3 adrenaline receptors and a high selectivity for β3 adrenaline receptors, wherein R1 represents hydrogen or halogeno; R2 represents hydrogen, hydroxy, lower alkoxy, lower alkoxy substituted by one or two lower alkoxycarbonyl or carboxy groups, lower alkoxy substituted by lower alkylaminocarbonyl optionally substituted by lower alkoxy, lower alkoxy substituted by cyclic C4-6 aminocarbonyl, lower alkoxycarbonyl, or carboxy; R3 represents hydrogen, hydroxy, lower alkoxy, or lower alkoxy substituted by one or two lower alkoxycarbonyl or carboxy groups, or R2 and R3 may be bonded to each other to thereby form methylenedioxy substituted by carboxy or lower alkoxycarbonyl; and m and n are each 0 or 1.