Disclosed herein are a method, an apparatus and a storage medium for image encoding/decoding using a palette mode. Prediction using a palette mode may be performed for a target block. Various types of predictions may be performed for the target block, and pieces of information to be signaled from an encoding apparatus to a decoding apparatus may be changed depending on the type of prediction to be performed for the target block. Determination of the pieces of information to be signaled may be optimized for the case where a palette mode is to be used for the target block, and thus efficiency of image encoding and decoding may be improved.