A method of decoding a video signal, comprising: deriving motion information of a current block in an enhanced layer based on motion information of corresponding blocks in a base layer, the motion information including a motion vector and a reference index; and reconstructing the current block using the derived motion information, wherein a ratio of a spatial resolution between the base layer and the enhanced layer is not multiple of 2, and wherein a corresponding block in the base layer is a block that has a region covering the current block in the enhanced layer when the corresponding block is magnified according to the ratio of the spatial resolution between the base layer and the enhanced layer, characterized in that: a reference index of a base layer block corresponding to a maximal number of current block pixels among the corresponding blocks in the base layer is selected as a reference index of the current block in the enhanced layer, and if the maximal number of current block pixels corresponds to two or more blocks in the base layer, the nearer reference index is selected, a motion vector of the block having the selected reference index is selected as a motion vector of the current block in the enhanced layer, and when a number of blocks having the selected reference index is two or more from among the corresponding blocks in the base layer, a motion vector having the shortest length among the motion vectors of the blocks having the selected reference index is selected as the motion vector of the current block in the enhanced layer. deriving motion information of a current block in an enhanced layer based on motion information of corresponding blocks in a base layer, the motion information including a motion vector and a reference index; and reconstructing the current block using the derived motion information, wherein a ratio of a spatial resolution between the base layer and the enhanced layer is not multiple of 2, and wherein a corresponding block in the base layer is a block that has a region covering the current block in the enhanced layer when the corresponding block is magnified according to the ratio of the spatial resolution between the base layer and the enhanced layer, characterized in that: a reference index of a base layer block corresponding to a maximal number of current block pixels among the corresponding blocks in the base layer is selected as a reference index of the current block in the enhanced layer, and if the maximal number of current block pixels corresponds to two or more blocks in the base layer, the nearer reference index is selected, a motion vector of the block having the selected reference index is selected as a motion vector of the current block in the enhanced layer, and when a number of blocks having the selected reference index is two or more from among the corresponding blocks in the base layer, a motion vector having the shortest length among the motion vectors of the blocks having the selected reference index is selected as the motion vector of the current block in the enhanced layer. a reference index of a base layer block corresponding to a maximal number of current block pixels among the corresponding blocks in the base layer is selected as a reference index of the current block in the enhanced layer, and if the maximal number of current block pixels corresponds to two or more blocks in the base layer, the nearer reference index is selected, a motion vector of the block having the selected reference index is selected as a motion vector of the current block in the enhanced layer, and when a number of blocks having the selected reference index is two or more from among the corresponding blocks in the base layer, a motion vector having the shortest length among the motion vectors of the blocks having the selected reference index is selected as the motion vector of the current block in the enhanced layer.