An image decoding device for increasing decoding efficiency and reducing the number of memory accesses includes a division unit dividing a picture into first and second coded image data; and first and second decoding units decoding, in parallel, the first and second coded image data and storing decoding results into a frame storage unit. The first and second decoding units decode the first and second coded image data using second and first decoding result information, respectively, and store the resulting first and second decoding result information into an information storage unit. When decoding a target macroblock, each of the first and second decoding units performs image processing on the corresponding second or first decoding result information indicating part of the decoded macroblock included in the macroblock line adjacent to the macroblock line including the target macroblock, and the target macroblock.