PURPOSE: To add or delete data in a buffer memory while reducing the quantity of pointer registers by processing plural storage element lists as a linked list.

CONSTITUTION: All storage elements 100-10m of a buffer memory 10 form a linked storage element list as a whole. Then data are read or written from/to a head storage element of a prescribed storage element list by referencing to list pointers 200-20m stored in pointer storage sections 120-12m of each storage element of the memory 10. Then a storage element whose read or write is finished to the end of other prescribed storage element list. Thus, addition/ delete of data in the buffer memory is attained in this way.