A method and apparatus for partially up/downscaling an image encoded on a macroblock basis. The method and apparatus performs operations of: storing the encoded image; creating map data from bitstream of the encoded image to decode at a least one macroblock of the encoded image, creating a shrunken image of a predetermined size based on resolution of a display device, storing the map data and the shrunken image so as to relate with the encoded image; outputting the shrunken image related with the encoded image to be displayed based on a control request received from an input device; determining at least one macroblock to be decoded based on a display area of the shrunken image; partially decoding the encoded image for the determined macroblock using the map data; and outputting to the display device, the image data of the display area of the partially decoded image.