In a transmission apparatus of a Gigabit Ethernet signal, in order to improve line efficiency, time division multiplexing is used. Further, if it is possible to branch/insert plural multiplexed Gigabit Ethernet signals at arbitrary nodes, it is possible to construct a more flexible network. For this reason, importance of a time division multiplexing apparatus having a function of branching/inserting Gigabit Ethernet signals is growing. A Gigabit Ethernet signal is monitored at the previous and subsequent stages of a cross connect unit, IFGs are inserted to the signal and switching is waited. If a signal state at the cross connection unit is an IFG, transmission path switching is performed, thereby performing transmission path switching without instantaneous interruption.