An image processing apparatus includes a division unit configured to divide an input image into a plurality of subblocks subjected to quantization control a subblock quantization parameter calculation unit configured to calculate a quantization parameter of each of the subblocks, a basic block quantization parameter calculation unit configured to set a basic block including at least two subblocks and to calculate a quantization parameter of the basic block, a difference value calculation unit configured to calculate a difference value between the quantization parameter of the basic block and the quantization parameter of each subblock included in the basic block, and a difference value coding unit configured to code the difference value.