An image encoding method is provided, in which image data divided into basic blocks is classified in units of groups and subgroups, wherein each group comprises at least one basic block and each subgroup comprises at least one basic block and is included in each group; an encoding mode for a predetermined group is determined in order to encode the predetermined group, wherein the encoding mode represents a mode for encoding data included in the predetermined group in units of one data processing unit selected from a group, a subgroup, and a basic block; and the data of the predetermined group is encoded according to the determined encoding mode. Detailed operations in the image encoding method are performed in consideration of the encoding mode of the group.