Disclosed is a high efficiency video coding (HEVC) encoding device including a candidate group updater configured to select a plurality of representative modes as a candidate group from among intra-prediction modes and update the candidate group using a plurality of minimum modes selected from the candidate group, the plurality of representative modes each representing a range where there is an optimal mode, and an optimal mode selector configured to select any one mode as an optimal mode from among a plurality of minimum modes selected from the updated candidate group.