The present invention relates to an ultrasonic diagnosis apparatus for radiating ultrasonic waves in a cross section of a subject by color Doppler scan, detecting the intensity of reflected echo, and brightness-modulating the intensity of the reflected echo, thereby obtaining a tomogram of the subject, and also for detecting a frequency-deviation (Doppler shift) of the reflected echo and detecting the direction and flow velocity of a blood flow in the subject, thereby displaying the blood flow two-dimensionally by coloring the blood flow portion in the tomogram in accordance with the detected flow velocity and direction. The apparatus of the present invention has a control means for controlling the scan-timings for B-mode scanning and CFM scanning independently, and thus, the frame rate for B-mode scanning and that for CFM scanning are controlled independently. The B-mode scanning frame rate can be controlled to be higher than CFM scanning frame rate. Therefore, the realtime following ability for displaying B-mode image is improved compared to the conventional color Doppler scan.