PURPOSE: To provide an ATM exchange in which the processing of RM cells is conducted with much more sophistication flexibly in place of not guaranteeing a transfer order between a backward RM cell and a data cell by applying processing to a separated backward resource management cell and inserting a backward cell between ATM cells other than the backward resource management cell.

CONSTITUTION: An ATM cell received from the outside of a cell switch via an ATM cell input A is outputted from an ATM cell output A. The ATM cells other than a backward RM cell and outputted via an ATM cell buffer section A. An identification separate section 21 identifies whether or not a cell is the backward RM cell. In the case of the backward RM cell, the cell is stored not in the ATM cell buffer section A but in an ATM cell buffer section D. The backward RM cell processed by a processing section 30 is processed by a processing means between an ATM cell buffer section D and an ATM cell buffer section E and inserted to a path of cells other than the backward RM cells again.