An image encoding/decoding method and apparatus are provided. An image decoding method according to the present disclosure comprises determining whether a prediction mode of a current block is an intra block copy (IBC) mode based on information on the prediction mode of the current block, based on the prediction mode of the current block being an IBC mode, deriving motion information of the current block based on motion information of a corresponding block corresponding to the current block, and generating a prediction block for the current block, by performing IBC prediction based on the derived motion information of the current block. Based on absence of motion information of the corresponding block, the motion information of the current block is derived based on default motion information.