PURPOSE: To shorten a processing time and to reduce memory capacity by coding the prescribed number of original symbols based upon a specified variable length code table.

CONSTITUTION: The distribution parameter of original symbols A in each prescribed number of lines is estimated by Laplace distribution based upon a count value (number of data) (n) more than a reference value B or less than the reference value B. A variable length code table most close to the estimated distribution parameter is selected from a variable length code table group corresponding to plural groups of representative parameters previously selected and registered and the original symbols A are coded within a short time based upon the table. Consequently, the processing time can be shortened without checking the appearance probability of all the original symbols to be coded and the capacity of a buffer memory to be required for hardware processing can be reduced.