The present invention relates to a crystalline polymorph of 2-[4-[2-[[(1S,2R)-2-hydroxy-2-(4-hydroxy-phenyl)-1-methylethyl]amino]ethyl]phenoxy]acetic acid having strong diffraction peaks (diffraction angle: 2&thgr;±0.1°) at 10.8, 19.1, 19.3, 19.8, 20.6 and 27.0° in powder X-ray diffraction pattern, which has potent &bgr;2- and &bgr;3-adrenoceptor stimulating effects and is useful as an agent for relieving pain and promoting the removal of calculi in urolithiasis, and the like. For example, the crystalline polymorph can be prepared by hydrolyzing ethyl 2-[4-[2-[[(1S,2R)-2-hydroxy-2-(4-hydroxyphenyl)-1-methylethyl]-amino]ethyl]phenoxy]acetate phosphate by sodium hydroxide, adding an aqueous phosphoric acid solution at 40° C. and over, adding a mixed solvent of water and methanol or methanol to the resulting compound, and stirring the suspension at 40° C. to reflux temperature for 30 minutes to several hours.