According to the present invention, a diagnosis support device suitable for the comparison between different diseases and others are provided. In a diagnosis support device 1 according to the present invention, the input of an MRI brain image of a subject is received (step S1), and a shrinkage score, which represents the degree of shrinkage of the brain, is then calculated on the basis of the MRI brain image (step S2). Subsequently, sites to be compared in the brain are identified (step S3). Subsequently, a degree of shrinkage, which represents the degree of shrinkage of each of the identified sites, and a shrinkage ratio, which is a ratio between the degrees of shrinkage of the sites, are calculated and are then compared and displayed (step S4).