Method and device for encoding/decoding image

The invention relates to a method and an apparatus for encoding/decoding an image. The method of decoding an image includes: determining whether a merge mode is applied to a current block; when the merge mode is applied to the current block, determining whether geometric modification information is used for inter prediction of the current block based on geometric modification usage information of the current block; and when the geometric modification use information indicates that the geometric modification information is used for inter prediction of the current block, obtaining a prediction block of the current block within the decoding target picture by performing inter prediction based on the reference picture and the geometric modification information, and wherein the geometric modification information is derived from merge candidates among a merge candidate list of the current block, and the merge candidate list includes at least one spatial merge candidate derived by at least one neighboring block of th