PURPOSE: To reduce a buffer capacity and a delay time in a packet transmitter by transmitting a packet at a high speed just after communication by using a congestion avoiding variable speed network.

CONSTITUTION: A packet from an information source 1 is encoded at a variable speed, stored in a buffer 12 of a packet transmitter 11, and transmitted at a transmitting speed preliminarily decided by a variable speed meter 15 for evading congestion. At that time, the transmission of a dummy packet preliminarily generated by a dummy packet generator 14 from the dummy packet generator 14 is started just before communication is started, and when a user packet arrives, an allowable transmission capacity is increased. Thus, the delay time can be reduced by transmitting the packet at a high speed, and the capacity of the buffer 12 can be made compact by reducing the initially arriving and absorbing amounts.