Abstract: A variable length image coding system for multiplexing multi channel parallel data at a specified speed after making variable length coding, and capable of suppressing the variation of amount of code generated upon multiplexing to within a specified range. In order that the total output of the sub-buffer memories is suppressed to within a certain range, the bit calculator calculates the amounts of code generated from the coders of each of the variable length coder sets, selects suitable ones of the coders for the respective channels, and controls the selectors, the output time zones of data from the sub-buffer memories, and the multiplexer. The coder buffer memory reads data in synchronism with the transmission speed and controls the variable length coder sets by feedback or stops the output of data by supplying a dummy in order to prevent the overflow and underflow.