A multi-layer video encoding/decoding method and a multi-layer video encoding/decoding apparatus are provided. In the multi-layer video encoding method, image data is encoded to a multi-layer encoded image, at least one of encoded layers of a target output layer set is determined as an output layer, an index of at least three output layer subsets including at least one output layer from among the encoded layers of the target output layer set are generated based on the determined output layer, and a bitstream including the generated index and the multi-layer encoded image is generated.