An image diagnosis support device comprising: image acquisition means for acquiring a tomographic image including an organ of interest of an object, said organ of interest being the lungs of said subject; reference region extraction means for extracting a reference region representing a reference in the organ of interest from the tomographic image acquired by the image acquisition means; organ region extraction means for extracting an organ region being lung fields representing the organ of interest from the tomographic image acquired by the image acquisition means; organ shape information calculation means for calculating organ shape information regarding the shape of the organ of interest from the reference region extracted by the reference region extraction means and the organ region extracted by the organ region extraction means; and display control means for displaying on a display device the organ shape information calculated by the organ shape information calculation means, characterised in that the reference region extraction means is adapted to extract a rib region by performing threshold processing on the tomographic image, and to extract a reference line corresponding to said reference region by connecting end portions of the rib region or points near the end portions; the organ shape information calculation means is adapted to calculate the thickness of the thoracic wall, for the entirety of the thoracic wall, by performing, for the points from a back-side point to a front-side point along the reference line, a threshold processing along straight lines from said points towards a centroid of the lung field, and the image diagnosis support device further comprises warning means for performing warning processing when the organ shape information calculated by the organ shape information calculation means does not satisfy a predetermined condition, by displaying, on a three-dimensional image of the object displayed on the display device, a warning display in which the organ shape information does not satisfy the predetermined condition, the warning display being displayed as an anomalous portion in an identifiable manner. image acquisition means for acquiring a tomographic image including an organ of interest of an object, said organ of interest being the lungs of said subject; reference region extraction means for extracting a reference region representing a reference in the organ of interest from the tomographic image acquired by the image acquisition means; organ region extraction means for extracting an organ region being lung fields representing the organ of interest from the tomographic image acquired by the image acquisition means; organ shape information calculation means for calculating organ shape information regarding the shape of the organ of interest from the reference region extracted by the reference region extraction means and the organ region extracted by the organ region extraction means; and display control means for displaying on a display device the organ shape information calculated by the organ shape information calculation means, characterised in that the reference region extraction means is adapted to extract a rib region by performing threshold processing on the tomographic image, and to extract a reference line corresponding to said reference region by connecting end portions of the rib region or points near the end portions; the organ shape information calculation means is adapted to calculate the thickness of the thoracic wall, for the entirety of the thoracic wall, by performing, for the points from a back-side point to a front-side point along the reference line, a threshold processing along straight lines from said points towards a centroid of the lung field, and the image diagnosis support device further comprises warning means for performing warning processing when the organ shape information calculated by the organ shape information calculation means does not satisfy a predetermined condition, by displaying, on a three-dimensional image of the object displayed on the display device, a warning display in which the organ shape information does not satisfy the predetermined condition, the warning display being displayed as an anomalous portion in an identifiable manner.