Disclosed is a method for decoding an image block. The method comprises a step of decoding an image block of a first layer based on a corresponding block of a second layer encoded with an intra mode, wherein a first area is formed with pixels, which are adjacent to a corner pixel positioned in the corresponding block in a diagonal direction and extend in vertical and horizontal directions away from the corresponding block, and data are padded in the first area based on the corner pixel and the pixels positioned in the first area and at least one of first and second blocks, which are simultaneously adjacent to the corresponding block and encoded with the intra mode. Accordingly, a reference block required when a macro block is encoded in an intra base mode or when a macro block encoded in the intra base mode is decoded has more precise values, thereby enabling improvement of a coding efficiency.