A hydroxyphenylpropionic ester represented by the formula of ##STR1## which has a crystal structure showing a sharp X-ray diffraction peak at a diffraction angle 2.theta.=7.9.degree. by X-ray diffraction measurement using an X-ray of a Cu-K.sub..alpha. wavelength. This novel crystal exhibits largely advantageous effects in industrial production and usage of the ester because of its high purity, high quality, excellent filterability owing to the large crystal growth, and excellent fluidity owing to the large bulk specific gravity.