Provided is a method that derives an intra prediction mode of a prediction unit, selects an inverse scan pattern of a current transform unit among a diagonal scan, a vertical scan and a horizontal scan based on the intra prediction mode and a size of the transform unit, and generates a quantized block by inversely scanning significant flags, coefficients signs and coefficient levels according to the selected inverse scan pattern. If the transform unit is larger than a predetermined size, multiple subsets are generated and inversely scanned. Therefore, the amount of coding bits of the residual block is reduced by determining the scan pattern based on the size of the transform unit and the intra prediction mode, and by applying the scan pattern to each subset. Also, the signaling bits decreases by generating MPM group adaptively according to the neighboring intra prediction modes.