A video encoding apparatus includes an inter predictor to check for availability of merge candidates configured from neighboring blocks of a current block, add into a merge candidate set, as one of the merge candidates, a combined bi-predictive motion parameter with respect to an unavailable block, the combined bi-predictive motion parameter generated by combining a list 0 motion parameter of a first available andidate block and a list 1 motion parameter of a second available candidate block, when the unavailable block is checked to be present among the merge candidates, and predict the current block by using a motion parameter corresponding to a merge candidate selected from the merge candidates including the combined bi-predictive motion parameter, to thereby generate a predicted block for the current block.