A video encoding method and apparatus and video decoding method and apparatus to generate a restored image having a minimum error with respect to an original image. The video decoding method includes: parsing offset merge information indicating whether offset parameters of a current block and at least one neighboring block from among blocks of video are identical to each other from a received bitstream; restoring an offset type and offset values among the offset parameter of the current block based on the offset merge information; determining an edge class or a pixel value band of a restored pixel based on an edge type or a pixel value band type of the current block indicating the offset type; and determining an offset value corresponding to the edge class or the pixel value band of the restored pixel from the offset values and adjusting a pixel value of the restored pixel according to the offset value.