A bandwidth variable communication apparatus includes: a route exchange unit including a route exchange function for switching an output port of a stream signal of one or more wavelengths input from an input port based on both or a part of wavelength and time, and including a bandwidth change function for changing passable frequency bandwidth in a section from the input port to the output port through which the stream signal passes; and a control unit including a control information transmit-receive function for transmitting and receiving control information for both or a part of the route exchange function and the bandwidth change function of the route exchange unit, and including a control function for controlling the route exchange unit based on the control information. All or a part of the input ports and the output ports are connected to other communication apparatuses via transmission routes.