A video decoding device and method, including extracting PCM block size information including a threshold, from a bitstream, determining the threshold based on the extracted PCM block size information; parsing a PCM header from the bitstream with respect to an encoded block, only when said encoded block is prediction mode of intra prediction and a block size of said encoded block is equal to or greater than the determined threshold, controlling an entropy decoding process and a PCM decoding process based on the parsed PCM header; parsing transformed data of a prediction error data of an image in the bitstream; and PCM-decoding PCM data of the image in the bitstream, wherein the decoding performs the decoding operation based on the prediction mode being intra prediction and based on the block size of the encoded block being equal to or greater than the determined threshold.