To attain coding and decoding efficiency similar to that by an arithmetic coding system and to improve considerably coding and decoding speed.

The method is made up of a prediction-setting process, in which multi-value information source is divided into bit planes or level planes, and either of '0' or '1' of each plane is used for a superior symbol, n-sets of consecutive symbols are predicted and the value (n) is set as a predicted bit number run, a prediction result output process where either '0' or '1' signal is outputted as a prediction hit signal when the prediction of a noted series is hit, a succeeding bit string is coded, and the other signal is outputted as a blank signal when the prediction is not hit. A similar prediction-setting process and a similar prediction output process are recursively repeated by using a new reduced prediction bit number smaller than the value (n), when the prediction is not hit for a prescribed number of times. When the prediction bit, a similar prediction setting process and a similar prediction output process are repeated by using a new increased prediction bit number. Furthermore, in the case of decoding, similar algorithm is applied to decoding.