A method of encoding a video, the method comprising: generating a skip flag for a coding unit which indicates whether the coding unit is encoded according to a skip mode; and when the coding unit is encoded according to a non-skip mode, generating information about a partition type and merge information of a partition, the merge information of the partition indicating whether the partition among one or more partitions is encoded in a merge mode, and when the partition is encoded in the merge mode, generating a merge index indicating one block among a candidate block group for the partition, wherein, motion prediction on the partition is performed by using motion information of the block which the merge index indicates, the information about partition type indicates the one or more partitions, including the partition, determined by splitting the coding unit, characterized in that the candidate block group for the partition includes one or more blocks from among the following three neighboring blocks of the partition: a left-lower block located on a left side of a leftmost block among lower blocks directly below a lower border of the partition, the left-lower block being located below a lowermost block among left blocks adjacent to a left border of the partition, a left-upper block located on a left side of a leftmost block among upper blocks directly above an upper border of the partition, the left-upper block being located above an uppermost block among the left blocks adjacent to the left border of the partition, and a right-upper block located on a right side of a rightmost block among the upper blocks directly above the upper border of the partition. generating a skip flag for a coding unit which indicates whether the coding unit is encoded according to a skip mode; and when the coding unit is encoded according to a non-skip mode, generating information about a partition type and merge information of a partition, the merge information of the partition indicating whether the partition among one or more partitions is encoded in a merge mode, and when the partition is encoded in the merge mode, generating a merge index indicating one block among a candidate block group for the partition, wherein, motion prediction on the partition is performed by using motion information of the block which the merge index indicates, the information about partition type indicates the one or more partitions, including the partition, determined by splitting the coding unit, characterized in that the candidate block group for the partition includes one or more blocks from among the following three neighboring blocks of the partition: a left-lower block located on a left side of a leftmost block among lower blocks directly below a lower border of the partition, the left-lower block being located below a lowermost block among left blocks adjacent to a left border of the partition, a left-upper block located on a left side of a leftmost block among upper blocks directly above an upper border of the partition, the left-upper block being located above an uppermost block among the left blocks adjacent to the left border of the partition, and a right-upper block located on a right side of a rightmost block among the upper blocks directly above the upper border of the partition. a left-lower block located on a left side of a leftmost block among lower blocks directly below a lower border of the partition, the left-lower block being located below a lowermost block among left blocks adjacent to a left border of the partition, a left-upper block located on a left side of a leftmost block among upper blocks directly above an upper border of the partition, the left-upper block being located above an uppermost block among the left blocks adjacent to the left border of the partition, and a right-upper block located on a right side of a rightmost block among the upper blocks directly above the upper border of the partition.