Provided is an apparatus for decoding an image. The apparatus restores a plurality of sub-blocks by applying a scan pattern determined according to the intra prediction mode of the current block on the quantization coefficient sequence and restores the quantized transform block by applying a scan pattern determined according to the intra prediction mode of the current block on the plurality of sub-blocks. Therefore, it is possible to reduce the amount of coding bits and computing resources required to decode a current prediction block.