Abstract: In a variable-length coding/decoding device, an r.multidot.m-bit data word is converted into an r.multidot.n-bit code word, where r is an integer having the relationship 1.ltoreq.r.ltoreq.r.sub.max, a basic data word length consists of a m bits (m is a positive integer), and a basic code word length consists of n bits (n is a positive integer), and each of data words of a variable-length run-length-limited code limiting the run number of bits of a first value (e.g., "o") between successive bits of a second value (e.g., "1") in a binary-coded bit string generated by concatenation of code words after the conversion to a value no smaller than d and no larger than k into a code word corresponding to thereto. At that time, an input data word is once coded into an r.sub.max .multidot.q-bit (q is a positive integer) code word, and then divided into r.sub.max blocks each consisting of q bits, and a code word in each of the blocks is coded to obtain a variable-length run-length-limited code word.