Method of constructing merge list

An image decoding method using a merge mode, the method comprising:

• constructing a merge candidate list by using available spatial merge candidates and an available temporal merge candidate;
• generating a prediction block based on motion information derived by using the merge candidate list,
• inversely quantizing a quantization block by using a quantization parameter generated per quantization unit, wherein the quantization block is generated with quantization coefficient components;
• generating a residual block by inversely transforming the inversely quantized quantization block;
• deriving a reconstructed block by using the prediction block and the residual block,
• wherein the spatial merge candidates are motion information of spatial merge candidate blocks, and the spatial merge candidate blocks are a left block, an above block, an above-right block, a left-below block or an above-left block of a current block,
• wherein a reference picture index of the temporal merge candidate is 0,
• wherein the quantization parameter is generated using a differential quantization parameter and a quantization parameter predictor, and the quantization parameter predictor is generated by using a left quantization parameter and an above quantization parameter if the left and the above quantization parameters are available,
• wherein, when only one of the left quantization parameter and the above quantization parameter is available, the quantization parameter is generated using the available quantization parameter and a previous quantization parameter, and
• wherein, when the left and above quantization parameters are not present, the previous quantization parameter is set as the quantization parameter predictor,