1. An inter-layer decoding method comprising: reconstructing a color image and a depth image of a first layer, based on encoding information about the color image and the depth image of the first layer, wherein the encoding information is obtained from a bitstream; determining, from the depth image of the first layer, a depth image block of the first layer which corresponds to a current block of a second layer image to be decoded; determining whether an area included in the determined depth image block of the first layer deviates from a boundary of the depth image of the first layer; when the area included in the depth image block deviates from the boundary, determining a depth value of the area deviating from the boundary of the depth image; determining a disparity vector indicating a corresponding block of the first layer image with respect to the current block, based on the determined depth value of the area deviating from the boundary of the depth image; and reconstructing the current block by using the disparity vector.