Provided is an encoder includes: circuitry; and memory, in which the circuitry: determines which mode is used to perform a prediction process, among modes including a first mode in which the prediction process is performed based on a motion vector of each block in a video and a second mode in which the prediction process is performed based on a motion vector of each sub-block obtained by splitting the block; when the prediction process is performed in the first mode, determines whether to perform a correction process on a prediction image using a spatial gradient of pixel values in the prediction image obtained by performing the prediction process, and performs the correction process when it is determined to perform the correction process; and when the prediction process is performed in the second mode, does not perform the correction process.