Provided are an apparatus and method for compression-encoding a moving picture at high speed while minimizing image quality deterioration. In H.264 moving picture encoding, the apparatus and method perform rate-distortion optimization (RDO) indispensable for high-definition encoding by feedback prediction, and minimize the amount of discrete cosine transform (DCT)-inverse DCT (IDCT) calculation performed for RDO many times, thereby performing H.264 encoding at high speed.