An apparatus for decoding a moving picture, comprising: an inverse scanning unit configured to convert a quantized coefficients sequence into a two dimensional, 2D, quantized block by inversely scanning quantized coefficients; an inverse quantization unit configured to determine a quantization step size predictor, obtain a quantization step size by adding the quantization step size predictor and a received residual quantization step size, and inversely quantize the quantized block using the quantization step size; an inverse transform unit configured to restore a residual block by inversely transforming the inverse quantized block; an intra prediction unit configured to restore an intra prediction mode of a current prediction unit and to generate a prediction block of the current prediction unit according to the intra prediction mode of the current prediction unit when the current prediction unit is coded in intra prediction mode; and an adder configured to restore an image block by adding the restored residual block and a prediction block, wherein a first available quantization step size is determined as the quantization step size predictor of a current coding unit when scanning in the order of a left coding unit neighbored to a left side of the current coding unit, an above coding unit neighbored to an upper side of the current coding unit and a previous coding unit, wherein, when the transform unit block size is larger than 4x4, the quantized coefficients sequence is inversely scanned in the unit of 4x4 subset, and wherein a scan pattern for inversely scanning the quantized coefficients of each subset is selected based on the intra prediction mode of the current prediction unit, and wherein a scan pattern for inversely scanning a plurality of subsets is the same as the scan pattern for inversely scanning the quantized coefficients of each subset. an inverse scanning unit configured to convert a quantized coefficients sequence into a two dimensional, 2D, quantized block by inversely scanning quantized coefficients; an inverse quantization unit configured to determine a quantization step size predictor, obtain a quantization step size by adding the quantization step size predictor and a received residual quantization step size, and inversely quantize the quantized block using the quantization step size; an inverse transform unit configured to restore a residual block by inversely transforming the inverse quantized block; an intra prediction unit configured to restore an intra prediction mode of a current prediction unit and to generate a prediction block of the current prediction unit according to the intra prediction mode of the current prediction unit when the current prediction unit is coded in intra prediction mode; and an adder configured to restore an image block by adding the restored residual block and a prediction block, wherein a first available quantization step size is determined as the quantization step size predictor of a current coding unit when scanning in the order of a left coding unit neighbored to a left side of the current coding unit, an above coding unit neighbored to an upper side of the current coding unit and a previous coding unit, wherein, when the transform unit block size is larger than 4x4, the quantized coefficients sequence is inversely scanned in the unit of 4x4 subset, and wherein a scan pattern for inversely scanning the quantized coefficients of each subset is selected based on the intra prediction mode of the current prediction unit, and wherein a scan pattern for inversely scanning a plurality of subsets is the same as the scan pattern for inversely scanning the quantized coefficients of each subset.