A frame synchronization method in which a synchronization detection of a frame synchronization signal using one of n-multiplexed frame synchronization signals derived from a sequence of frame synchronization signals each delayed by one bit from the preceding frame synchronization signal, a synchronization confirmation as synchronization guard by detecting a repetition of the synchronization detections of the frame synchronization signal, a confirmation of the subsequent frame identification signal based on the synchronization confirmation; and a separation of the received multiplexed signals into a plurality of channels based on the synchronization confirmed frame synchronization signal and the confirmed frame identification signal are carried out.