An isoflavone derivative is provided. The isoxazole derivative has following formula: ##STR00001## wherein R.sub.1 and R.sub.2, independently, include C.sub.1-C.sub.12 alkyl optionally substituted with oxirane, thiirane, aziridine, amino, cycloamino, aminohydroxy or cycloaminohydroxy, and R.sub.3 includes hydrogen, hydroxy or C.sub.1-C.sub.12 alkoxy optionally substituted with oxirane, thiirane, aziridine, amino, cycloamino, aminohydroxy or cycloaminohydroxy. The invention also provides a pharmaceutical composition for treatment of osteoporosis including an isoflavone derivative or a pharmaceutically acceptable salt thereof and a pharmaceutically acceptable carrier.