PURPOSE: To reduce number of changeover circuits between a coder and a frame memory and to simplify the changeover control by copying small picture data to be referred to on a local frame memory of an n-th coder when the n-th coder refers to a small picture other than the n-th small picture.

CONSTITUTION: A picture divider 1 divides an input picture into pieces (N is an integer being 2 or over) of small pictures, an n-th (n=0-n) coder 2 codes an n-th small picture, a reproduced n-th small picture is stored in an n-th frame memory 4 connecting to the n-th coder 2, and a multiplexer 5 multiplexes outputs of N-sets of coders 2 and sends the result to a transmission line. The N-sets of coders 2 are connected by data buses 6 in the system and when the n-th coder 2 references a picture of the m-th(mn) frame memory 4, after the picture to be referenced is copied to the n-th frame memory 4 via the m-th and n-th coders 2, the coding is continued.