A method for decoding a video according to the present invention may comprise: deriving a spatial merge candidate for a current block, generating a merge candidate list for the current block based on the spatial merge candidate, obtaining motion information for the current block based on the merge candidate list, and performing motion compensation for the current block based on the motion information. Herein, if the current block does not have a pre-defined shape or a size equal to or greater than a pre-defined size, the spatial merge candidate of the current block may be derived based on a block which have the pre-defined shape or a size equal to or greater than the pre-defined size, the block including the current block.