PURPOSE: To reduce the capacity of a memory which stores information on restoration of editing data by dividing a received editing request into reversible basic action units and at the same time storing sequentially those information on the editing actions.

CONSTITUTION: The editing actions set to an editing request are divided by an editing analyzing part 1 into the editing units that can be reversible operated and then sent successively to an editing processing part 2 as the editing information showing each editing action. The part 2 edits a file based on the received editing information and at the same time stores the editing information in an editing information memory buffer 3 via an editing information control part 4. IF a file restoring request is given to the part 1 from a user, the part 4 replaces the editing information stored in the buffer 3 with the information showing an adverse action. This editing information is sent to the part 2 in the adverse order to that of the storage and an edited file is restored. Thus the memory capacity for storage of data can be reduced.