1. A medical image judging apparatus, comprising: memory means, for recording a medical image that includes an image of a predetermined diagnostic region, which is a target of diagnosis, therein; structural element extracting means, for extracting at least one anatomical structure comprising a breast and pectoral major muscle from within the medical image; judging means, for judging whether the diagnostic region comprising a breast within the medical image is appropriate for conducting diagnosis, with the extracted structural element as a reference; judgment result output means, for outputting the judgment results obtained by the judging means; and wherein: the judging means judges whether the at least one extracted anatomical structure within the diagnostic region within the medical image includes anatomical structures within a range which is appropriate for use in conducting diagnosis; and wherein: the medical image is a mammogram; the structural element extracting means extracts a pectoral major muscle and a breast; and the judging means performs judgment, based on the ratio of the area of the pectoral major muscle to the area of the breast within the diagnostic region.