PURPOSE: To provide a back-up system which effectively backs up the production of a diagram.

CONSTITUTION: A diagram production tool is provided with an electronic computer contains an input means 1, an input processing means 2, an editing processing means 3, a display switch means 4, a semantic information file 5, a display information file 6, a synthesization processing means 7, a display processing means 8, and a display means 9. The means 3 rewrites the files 5 and 6 in accordance with an inputted editing operation. When an OFF state is set, the means 4 deletes the information on an OFF part out of the file 6. The means 8 erases the OFF part out of a screen. When a full display request is inputted, the means 7 calculates the display position of each element based on the semantic information stored in the file 5 so that the duplication of elements is minimized. Then the means 8 executes the full display based on the result of the calculation.