The multi sample prediction method of the present invention comprises the steps of: determining a sample group consisting of a plurality of samples inside a decoding target block; determining a representative position corresponding to the sample group, inside the decoding target block; determining a representative prediction value for the sample group, on the basis of the determined representative position; and determining the determined representative prediction value as the final prediction value for each of the plurality of samples making up the sample group. The present invention enhances efficiency in encoding/decoding and reduces complexity thereof.