1. A medical image processing device, comprising: an input means for inputting a brain image of a test subject, the brain image being made up of voxels, each of the voxels having a respective value; a segmentation means for segmenting gray matter tissue by performing a tissue segmentation process on the brain image of the test subject and creating a resultant tissue segmented image; a memorizing means for saving an image group of gray matter tissues of healthy subjects; a memorizing means for saving normal tissue segmentation images; an output means for outputting diagnosis support information based on statistical comparison between the resultant tissue segmentation image of the test subject obtained by the segmentation means and the image group of gray matter tissues of healthy subjects; and a distinguishing means for distinguishing between normal and abnormal results or segmentation by the segmentation means, based on the voxel value of the resultant tissue segmented image for the brain image of the test subject and per-voxel statistical value of the normal tissue segmentation images, wherein a per-voxel statistical value of the normal tissue segmentation images is represented, at every position, by an average value and a standard deviation of respective distribution of the voxel values according to a position to which each image of the normal tissue segmentation images corresponds, and then the distinguishing means distinguishes between normal and abnormal results of segmentation by the segmentation means by comparing, against a predefined threshold value, an average value over the whole of the resultant tissue segmented images of an absolute Z-score determined from the voxel value of the resultant tissue segmented image for the brain image of the test subject, and the average value and the standard deviation at a position to which the normal tissue segmentation images corresponds.