provided is a maximum likelihood decoding method that includes the steps of ; firstly arranging channel impulse responses corresponding to the received signals in a plurality of different orders ; secondly specifying the same number of parts as the plurality of different orders in which the channel impulse responses are arranged , so that the received signals are placed in each of the parts ; thirdly generating channel matrices each having the channel impulse responses as matrix elements , by using the channel impulse responses arranged in the plurality of different orders , obtaining triangular matrices by applying qr decomposition to the generated channel matrices , and determining at least one combination candidate for each of the parts of the plurality of transmission signals by using the obtained triangular matrices ; and fourthly selecting the combination candidates so that a euclidean distance between the combination candidates determined in the third step is shortest .