1. An ultrasonic diagnostic apparatus for transmitting an ultrasound signal to a diagnosis target and receiving a reflected ultrasound signal from the diagnosis target to generate an ultrasound image, the ultrasonic diagnostic apparatus comprising: a display including a screen comprising of plural pixels; a probe; a beam former; a processor connected to the probe and configured to signal-process frame data generated by the beam former to generate ultrasound image data and obtain blood-flow information at plural division positions on the diagnosis target corresponding to respective division regions obtained by dividing an ultrasound image to be displayed on the screen, wherein each of the division positions is a preset unit of plural pixels on the screen of the display; and filters configured to filter the ultrasound image data using filtering masks, which are determined corresponding to each of the division positions based on the blood-flow information at each of the division positions, to generate one or more filtered ultrasound image data, wherein the display is configured to display the ultrasound image on the screen, wherein the ultrasound image is synthesized by acquiring the divided images corresponding to the respective division position from the respective filtered ultrasound image data and allocating the divided images to the corresponding division regions on the screen, respectively.