In a common buffering device with a simple arrangement, a write address can be efficiently released from a buffer memory upon receipt of a multi-address call. For an ATM cell which is to be transmitted to a specific line, a write address is set in a common buffer memory, and the ATM cell is written at the write address. The ATM cell is read from an address which corresponds to the write address, and is transmitted to the specific line. Then, the pertinent write address is released. In a write table are entered a plurality of multi-address lines across which an ATM cell written at a specific address in the common buffering device can be multicast. Each time the ATM cell is read from the specific address, a designation line for transmission of an ATM cell in a read control table is compared with the multi-address lines set in the write control table. When the lines match, the write address for the ATM cell, which is set in the write control table, is released.