A coded stream analyzer (102) variable-length decodes an incoming coded stream and extracts encoding parameters for each macroblock, such as an encoding mode, DCT coefficient values, the amount of codes of DCT coefficients, the amount of codes of each macroblock, and a motion vector, from the coded stream. An effective macroblock identification unit (103) then identifies macroblocks each of which can be contained in a moving object as an effective macroblock by using one or more encoding parameters extracted by the coded stream analyzer (102). A moving object determination unit (104) determines whether or not each of the one or more effective macroblocks identified by the effective macroblock identification unit (103) is contained in a moving object by counting the number of effective macroblocks which are directly adjacent to each of the one or more effective macroblocks or indirectly adjacent to each of the one or more effective macroblocks via one or more other effective macroblocks, and then comparing the number of adjacent effective macroblocks with a predetermined threshold value.