A multiplex signal transmission system in which a plurality of information signals, having respectively arbitrary time durations and being arranged in time-serial form, are sequentially divided into a plurality of signal portions by a predetermined time period, said signal portions being successively allocated in time-parallel form to a plurality of transmission channels, each of which has a time duration of said predetermined time period, and being transmitted repeatedly through respectively allocated channels every said time duration, comprises a channel shift means for shifting sequentially the channel allocation of said signal portions at predetermined time periods, and a signal transmitting means for transmitting in time-parallel form said signal portions derived from said channel shift means repeatedly through every preceding channels. Consequently, the transmission line can be efficiently utilized in such a way that, at the sending end, a plurality of information signals having respectively arbitrary time durations are folded into a plurality of transmission channels having given time periods, and besides that, at the receiving end, once a portion of any desired information signal is caught in a corresponding channel, successive signal portions can be derived sequentially from the same channel every said given time periods. Hence, a channel selecting means of a receiver in this system can be simplified.