IMAGE DECODING APPARATUS, IMAGE DECODING METHOD, IMAGE CODING APPARATUS, AND IMAGE CODING METHOD

To provide an image decoding apparatus that suppresses overhead of parallel processing to improve parallelization efficiency and reduce circuit costs, while solving neighboring macroblock dependencies. The image decoding apparatus (100) includes first and second decoding circuits (101, 102) having a transfer unit that transfers right neighborhood information or left neighborhood information, and first and second transfer completion detection units (104, 105) that respectively detect whether or not the left neighborhood information or the right neighborhood information has been transferred to the first and second decoding circuits (101, 102). Each of the first and second decoding circuits (101, 102) decodes a decoding target macroblock positioned at an edge of a region, when the transfer of the left neighborhood information or the right neighborhood information is detected. A boundary line between regions is orthogonal to a decoding direction corresponding to an order in which macroblocks adjacent to each other are sequentially decoded.