PURPOSE: To facilitate three-dimensional recognition of the running condition of blood vessels on a colored angio-image.

CONSTITUTION: An ultrasonographic diagnostic device superposes, per frame, plural pieces of blood-flow images obtained by plural scanning section in parallel with a scanning section opposed the projected direction of a three-dimensional diagnostic site and displays them as angio images. This diagnostic device is provided with plural frame memories 141-14n, and a memory means in which plural pieces of blood-flow image data are memorized respectively (control part 10, multiplexer 13), a designating means for designating at least either an initiating frame for superposing the blood-flow images or a terminating frame (inputting apparatus 16, control part 10), a superposing means for superposing the blood-flow image data between the initiating frame and the terminating frame on the basis of the designated frame (angio image creating circuit 15), and a displaying means for displaying the superposed blood-flow image (RGB transducer 12, D/A transducer 17, displaying apparatus 18).