PURPOSE: To accurately count a cell flow from a calling of one call to its inter ruption by using a call identification number given at the calling and flag infor mation representing whether the call is continued or terminated to manage a count of a counter in a cell count section in an exchange node.

CONSTITUTION: When a setup is finished and communication is started, the information of the user is converted into a cell form and it passes through a transmission line. When a cell 34 is inputted from an input transmission line 31, a label detection section 32 detects a label and it is sent to a cell count section 33. The count section 33 has a label A1 and selects a counter whose flag is set to 1 and increments the counter. The counter section 33 keeps the count till a network management node 36 reads the count section even when call interrupt (end of call) takes place.