PURPOSE: To uniformize the cell communication density by sequentially estimating and comparing a percentage delay of each communication path between outgoing and incoming exchange nodes for each call according to a traffic changing time to time in various ways and selecting a communication path with a minimum estimated value so as to connect the call.

CONSTITUTION: A path information reader 2 references a path table 3 based on identification information of a called exchange node from an input terminal 1 to read a coordinate of a relay exchange node forming plural communication paths to reach the called exchange node. Based on the coordinate, a load factor reader 4 references a load factor table 5 to read the load factor of a relay node of each communication path. Based on the load factor, a P delay calculation device 6 calculates a delay percentage reaching the called exchange node from its own node for each communication path. A P delay comparison minimum path discrimination device 7 compares delays based on the result of calculation and informs a minimum communication path to a cell exchange use connection table 8. Thus, the cell communication density in an in-network transmission line is uniformized.