An object of the present invention is to acquire information regarding the cardiac valve required in the clinical field, such as the tenting volume, tenting area, tenting height of the mitral valve of the heart, the area, the circumferential length, and height (the difference between the highest portion and the lowest portion) of the mitral annulus, etc. A method of obtaining a three-dimensional cardiac-valve image for measuring clinically required data regarding the cardiac valve, in which method a three-dimensional echocardiogram is created from two-dimensional echocardiograms obtained through scanning by means of an echocardiograph, and the three-dimensional cardiac-valve image is automatically extracted from the three-dimensional echocardiogram by computer processing The method is characterized in that a fitting evaluation function (potential energy) of a model of the mitral annulus in a fitting model prepared in consideration of the physical shapes of the heart and the mitral annulus is optimized by the replica exchange method and extended simulated annealing method.