A picture compressing apparatus compresses pictures which are classified into three types of pictures. They are an I picture that is intra-frame coded, a P picture that is forward inter-frame coded, and a B picture that is forward/backward inter-frame coded. An apparatus controlling device checks the ID of existing CPU 2 and the CPU ID of program currently created and determines whether or not they match. When the determined result is No, the apparatus controlling device extracts a compressed code of basic modules and differential modules corresponding to the existing CPU. With reference to a code table 17, a decoder decodes the compressed codes to generate an optimun program for the existing CPU. The picture reproducing apparatus performs the similar process to that of the picture compressing apparatus.