The present invention provides ethyl (-)-2-[4-[2-[[(1S,2R)-2-hydroxy-2-(4-hydroxyphenyl)-1-methylethyl]amino]e- thyl]-2,5-dimethylphenoxy]acetate hydrochloride, crystalline forms thereof and pharmaceutical compositions containing them, which have excellent .beta..sub.3-adrenoceptor stimulating effects, therapeutic effects on pollakiuria or urinary incontinence and storage stabilities and are useful as a medicament.