There is provided an ultrasound image processing apparatus which displays an ultrasonic image with a higher resolution. In a received frame, a first pixel array, a second pixel array, and a third pixel array are defined in depths different from each other. For each pixel of interest on the first pixel array, a pattern matching process is applied between the first pixel array and the second pixel array, to calculate a mapping address on the second pixel array for the pixel of interest. In addition, for each pixel of interest on the third pixel array, a pattern matching process is applied between the third pixel array and the second pixel array, to calculate a mapping address on the second pixel array for each pixel of interest. The second pixel array is re-constructed into a high-density pixel array using pixel values and mapping addresses of a plurality of pixels of interest.