The present invention combines an inter-prediction method using an AMVP mode and an inter-prediction method using a merge mode so as to use the same candidates. The method for decoding video data proposed by the present invention comprises receiving mode information on an inter-prediction method of a current block, determining, on the basis of the received mode information, whether the inter-prediction method to be applied to the current block is an AMVP mode or a merge mode, and selecting a candidate to derive motion information of the current block.