Abstract: In a time division multiplex transferring system which uses fixed setting, on-demand, and frame relay bandwidths, a first time switch allocates the on-demand and frame relay bandwidths in response to a first allocation setting datum to produce two output signals. A second time switch allocates the on-demand and frame relay bandwidths in response to a second allocation setting datum to produce two output signals. A bandwidth allocation controlling device produces and renews the first and second allocation setting data in response to the connectivity restriction to produce and transmit a first allocation change datum to a counter node. The bandwidth allocation controlling device thereafter produces a first allocation end signal in response to a second allocation end signal from the counter node.