Multilayer video encoding/decoding methods and apparatuses are provided. A multilayer video decoding method includes: obtaining inter-layer prediction allowance information from a bitstream; obtaining single layer use information from the bitstream when the inter-layer prediction allowance information indicates that inter-layer prediction is usable; determining at most only one layer among at least one layer, to which a current picture refers, as a reference layer when the single layer use information indicates that at most one picture is used for inter-layer prediction; and performing inter-layer prediction on the current picture by using a picture belonging to the reference layer.