Abstract: Disclosed is a time-division multiplexer for demultiplexing, into individual time slots, time-division multiplexed data in a receive direction received from a network via a trunk unit, and sending the data to a prescribed tributary unit, and for multiplexing, to a prescribed time slot, data in a transmit direction which enters from tributary units and sending the data to the network via the trunk unit. The time-division multiplexer has a trunk bus to which a trunk unit is connected and a tributary bus to which tributary units are connected, and a time-slot interchange unit provided between these buses, wherein interchange of cross-connected time slots on the trunk side and time slots on the tributary side is performed dynamically by the time-slot interchange unit.