PROBLEM TO BE SOLVED: To solve a problem that an apparatus which is obtained by incorporating a bone density measuring device into a conventional sphygmomanometry apparatus is thought, and a device which measures a bone density by receiving diffuse reflection light of an elbow part by making light be incident onto an elbow part exists, but these apparatuses do not give a shock to real bones so real bone strength cannot be measured.SOLUTION: In use of a sphygmomanometry apparatus which measures a blood pressure with a cuff in which an arm is inserted, a shock is given on an olecranon part, which is equivalent to arms egress of the sphygmomanometry apparatus, to generate a sound or oscillation at the olecranon. A sound or oscillation generated at an ulnar head at which the sound or oscillation propagated through the ulna from the olecranon is arrived is measured by an acoustic sensor or pressure sensor used in sphygmomanometry. A bone strength is measured from a relation between a distance between the olecranon and the ulnar head and a time from shock addition to detection.
