An image decoding method using artificial intelligence (AI), including obtaining feature data of a current optical flow and feature data of current differential data from a bitstream corresponding to a current image; obtaining the current optical flow by applying the feature data of the current optical flow to a neural-network-based first decoder; applying at least one of the feature data of the current optical flow and feature data of a previous optical flow to a first preprocessing neural network; obtain a first concatenation result by concatenating feature data obtained from the first preprocessing neural network with the feature data of the current differential data; obtaining the current differential data by applying the first concatenation result to a neural-network-based second decoder; and reconstructing the current image using the current differential data and a current predicted image generated from a previous reconstructed image based on the current optical flow.