The present invention provides video encoding and decoding methods using block merging, which can be applied to a high resolution video of more than HD (High Definition) resolution. A video encoding method includes partitioning a current block into a first and a second prediction unit by using asymmetric partitioning, constructing a list of common merging candidate blocks including a predetermined number of common merging candidate blocks selected from adjacent blocks of the current block, selecting at least one candidate block from among the list of common merging candidate blocks and sending information of the selected candidate block to a decoder for each of the first and the second prediction unit.