To provide the communication system that solves a problem of missing pulse in multiplexing used for position modulation of both positive negative pulses of each entire data frame and high speed transmission with a high efficiency is attained.

A set of pluralities of multi-value data symbols Si(S1...SM) where each symbol takes multi-values are converted into a set of pluralities of coded data symbols S'i(S'1...S'N) which correspond one to one to the data symbols Si(S1...SM) and take different values according to a prescribed coding rule, positions of pulses are modulated by a multiplex pulse position modulation system modulation section, multiplexed and sent to a transmission line. A multiplex pulse position modulation system demodulation section at a receiver side recover each of coded data symbols S'i(S'i...S'N) and a demodulation means decodes a set of the original multi-value data symbols Si according to a decoding rule inverse to the coding rule. Since pluralities of the coded data symbols S'i take different values, the overlapping of pulses is eliminated at multiplexing to eliminate a transmission error.