The disclosure has an object to provide a medical-data processing device that allows generation of an MIP image suitable for diagnosis. With the medical-data processing device of the disclosure, intensity of a body surface region in three-dimensional space data is adjusted. The body surface region corresponds to a body surface of a stereoscopic image of a subject. Since the intensity of the body surface region is adjusted to be decreased, the maximum intensity is selected from a portion except for the body surface region to generate the MIP image. This prevents the body surface of the subject from appearing upon generating the MIP image. Therefore, the MIP image is obtainable having excellent visibility to the inside of the subject.