Abstract: The present invention discloses method and apparatus for decoding multi-level trellis coded modulation having improved efficiency by parallel processing when decodes multi-level trellis coded modulation. The method and apparatus according to the present invention divide branches having the next state periodically using commonness among branches divided from the current state to the next state, and improve efficiency of decoder by the parallel processing unit for addition comparison selection according to the rate of code and the size of binding field based on this periodicity. And, the feature of the present invention is having the simplicity for hardware and the facility for constitution when constitutes the decoder to the large scale integrated circuit, by constituting data to be able to the series processing, produced from the operation of the unit for parallel addition comparison selection.