Disclosed is a prophylactic or therapeutic agent for osteoporosis having better pharmacological efficacy compared to a conventional prophylactic or therapeutic agent for osteoporosis which comprises soybean protein or soybean isoflavone as an active ingredient. There remains some double about the therapeutic effect of soybean isoflavone on osteoporosis which have been predicted based on the results given by test performed in small animals. Then, a novel soybean-derived ingredient which is effective for the prevention or treatment of osteoporosis is now specified using a primate model. A prophylactic or therapeutic agent for osteoporosis comprising ß-conglycinin and/or a protease hydrolysate thereof as an active ingredient, ß-conglycinin and/or the hydrolysate being contained in an amount of 15% by weight or more.
