1. An osteoporosis diagnosis aiding apparatus utilizing a panoramic radiograph of teeth, comprising: image region extracting means for extracting an image of a region including a specified portion in the panoramic radiograph of teeth; skeleton processing means for finding a skeleton of the extracted image; line extracting means for extracting only portions parallel to the tilt of the lower edge of the mandible from the found skeleton: binarizing means for binarizing an image including the skeleton so that lines of the skeleton are separated from the background; and determining means for determining whether there is a risk of osteoporosis by classifying the binarized lines according to size.