A medical diagnostic apparatus according to one embodiment comprises processing circuitry. The processing circuitry is configured to acquire a three-dimensional shape of a first part based on a contour of the first part in each of a plurality of sectional images intersecting each other along an extending direction of the first part connecting to a cardiac chamber; acquire a three-dimensional shape of a second part, based on a contour of the second part in a sectional image along an extending direction of the second part connecting to the cardiac chamber; and generate a three-dimensional image representing at least some of the first part, the second part, and the cardiac chamber using a three-dimensional shape representing the cardiac chamber and the three-dimensional shapes of the first part and the second part acquired.