PURPOSE: To attain the transmission of an efficient picture data and to simplify the circuit constitution by outputting an encoded brightness signal and a coded chrominance signal as to a picture element in a specific output mode.

CONSTITUTION: An encoder side sends, e.g. two blocks Y1a-Ysb of a brightness (Y) component in one upper block line and a chrominance (Cr, Cb) component corresponding to the blocks in pairs. Then Y components Y1c-Ysd in remaining one lower block lines is sent. A decoder side stores one block line each of two blocks of Y signal and the Cr, Cb signal to a buffer memory. In this case, the data corresponding to the one lower block line of the Cr, Cb signal is stored in a line memory. When the components Y1c-Ysd corresponding to the lower block line are sent, the required Cr, Cb data are read from the line memory and used. Thus, the capacity of the line memory at the decoder side is reduced.