The bone salt content determination device of the invention realizes that, in the determination of bone salt content, a predominant part in a cortical bone is excluded to the greatest possibility in a bone end part image, and a predominant part in a spongy bone is set as the ROI. The ROI setting unit (28) sets a contour extraction range (80) based on a plurality of feature points on an outline of the radius end image (62b) located in an X-ray image (60), the contour extraction range including a band high brightness region (70) of a cortical bone region produced along a wrist-side contour (62f) of the radius end image (62b), and excluding other high brightness regions located within the radius image (62). The ROI setting unit (28) extracts a plurality of high brightness pixels corresponding to the inside contour of the high brightness region (70) in the contour extraction range (80). The extracted plurality of high brightness pixels are described, so as to generate a trace (90) representing the inner shape of the high brightness region (70). The ROI setting unit (28) sets a frame (100) including the trace (90) as ROI.
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