Disclosed is a method for decoding a video, the method including: encoding video data of the maximum coding unit based on deeper coding units of hierarchical structures of at least one split region of the maximum coding unit, determining a coding depth by using partitions obtained by splitting the coding unit according to arbitrary ratios to execute inter-frame prediction; and outputting a bitstream including the encoded video data corresponding to the coding depth according to maximum coding units and information regarding the coding depth and encoding modes.