a transmission system includes : a first transmission device configured to transmit an input signal to a second transmission device via a transmission section , the first transmission device preforms operations of : saving overhead information included in a first frame of the input signal from a region in use to an unused region of the first frame , the overhead information corresponding to an object of termination in the transmission section ; and transmitting , to the transmission section , a first signal including a second frame in which the overhead information is saved .