The present invention relates to an apparatus for processing an ultrasound image of a target object including a periodically moving object, including: an ROI setting unit for setting regions of interest (ROIs) to each of frames constituting ultrasound volume data acquired from a target object; a VOI setting unit for selecting a predetermined number of first reference frames from the ultrasound volume data and setting a predetermined number of volumes of interest (VOIs) by combining ROIs of the first reference frames with ROIs of frames adjacent to the reference frames; a motion compensating unit for processing the VOIs to compensate a motion of the target object; a correlation coefficient curve calculating unit for calculating a correlation coefficient curve for a predetermined interval at each VOI; a period setting unit for setting a moving period of the moving object based on the correlation coefficient curve in the volume data; and an ultrasound volume data reconstructing unit for reconstructing the ultrasound volume data based on the moving period.