1. An apparatus for decoding an image, the apparatus comprising: a processor which determines coding units of a hierarchical structure, based on information about whether to divide a coding unit parsed from a received bitstream of an encoded video; a decoder which determines whether a current coding unit among the determined coding units of the hierarchical structure comprises a region that deviates from a boundary of a current image; wherein, if the current coding unit is determined to not comprise the region that deviates from the boundary of the current image based on the determining whether the current coding unit comprises the region, the decoder parses and decodes data regarding the current coding unit of the hierarchical structure; and wherein, if the current coding unit is determined to comprise the region that deviates from the boundary of the current image based on the determining whether the current coding unit comprises the region, the decoder determines sub coding units generated by dividing the current coding unit, that comprises the region that deviates from the boundary of the current image.