1. An interlayer video decoding method comprising: obtaining brightness compensation information indicating whether a second layer current block performs brightness compensation; determining whether a candidate of the second layer current block is usable as a merge candidate based on whether the brightness compensation information indicates that the brightness compensation is performed and whether the candidate of the second layer current block performs time direction inter prediction; generating a merge candidate list including at least one merge candidate based on a result of the determining; and determining motion information of the second layer current block by using motion information of one of the at least one merge candidate.