As described above, a second candidate group may include a plurality of candidate modes. First remaining mode information specifying any one of a plurality of candidate modes may be signaled. A candidate mode specified by signaled first remaining mode information may be set as an intra prediction mode of a current block. Alternatively, when first and second candidate groups are not used, second remaining mode information may be signaled. Second remaining mode information may specify any one of remaining modes other than candidate modes belonging to first and second candidate groups among intra prediction modes which are predefined in an encoding/decoding device. A candidate mode specified by second remaining mode information may be set as an intra prediction mode of a current block.
A method of determining the above-described second candidate group will be described by referring to 
The remaining mode information may be encoded based on remaining modes other than a second candidate group among the non-MPM or may be encoded based on a non-MPM that at least one of a second candidate group or a third candidate group is rearranged, which will be described by referring to