A method and apparatus for decoding a video and a method and apparatus for encoding a video are provided. The method for decoding the video includes: receiving and parsing a bitstream of an encoded video; extracting, from the bitstream, encoded image data of a current picture of the encoded video assigned to a maximum coding unit, and information about a coded depth and an encoding mode according to the maximum coding unit; and decoding the encoded image data for the maximum coding unit based on the information about the coded depth and the encoding mode for the maximum coding unit, in consideration of a raster scanning order for the maximum coding unit and a zigzag scanning order for coding units of the maximum coding unit according to depths.