1. An ultrasonic imaging apparatus comprising: an ultrasonic probe configured to receive an ultrasonic wave; an image processor configured to generate a plurality of ultrasonic images comprising at least a first ultrasonic image grouped into a first set of ultrasonic images according to the ultrasonic wave; an input unit configured to receive a selection command for selecting at least a second ultrasonic image as a second set of ultrasonic images from the first set of ultrasonic images according to a user's manipulation; and a display unit configured to display the first set of ultrasonic images in a first zone of a screen of the display unit, and the second set of ultrasonic images in a second zone of the screen of the display unit, wherein the first set of ultrasonic images comprises a plurality of first image frames belonging to a first group, and the second set of ultrasonic images comprises a plurality of second image frames belonging to the first group, and wherein the plurality of second image frames are displayed sequentially in the second zone.