A graphic display control apparatus, comprising: a formula display screen (Fig. 3: 50, Fig. 2: CW1) for displaying data in a formula format; a graphic display screen (Fig. 3: 50, Fig. 2: GW1) for displaying data in a graphic format; first specifying means (Fig. 6: A16) for specifying either one of the data in the formula format displayed on the formula display screen and the data in the graphic format displayed on the graphic display screen; second specifying means (Fig. 6: A20) for, after one of the data in the formula format and the data in the graphic format is specified by the first specifying means, specifying either of the formula display screen and the graphic display screen; graphic form conversion means (Fig. 3: 10) for, when the graphic display screen is specified by the second specifying means after the data in the formula format displayed on the formula display screen is specified by the first specifying means, converting the data in the formula format displayed on the formula display screen into corresponding data in the graphic format; formula form conversion means (Fig. 3: 10) for, when the formula display screen is specified by the second specifying means after the data in the second format displayed on the graphic display screen is specified by the first specifying means, converting the data in the graphic format displayed on the graphic display screen into corresponding data in the formula format; a display section (Fig. 3: 50) for displaying the formula display screen and the graphic display screen; and a tablet (Fig. 3; 30) for detecting a position of a point in a screen of the display section by drag and drop operations of an input pen, and wherein said first specifying means specifies either of the data in the formula format and the data in the graphic format based on the position of the point detected by the tablet while performing the drag operation of the input pen; and said second specifying means specifies either of the formula display screen and the graphic display screen based on the position of the point detected by the tablet while performing the drop operation of the input pen. a formula display screen (Fig. 3: 50, Fig. 2: CW1) for displaying data in a formula format; a graphic display screen (Fig. 3: 50, Fig. 2: GW1) for displaying data in a graphic format; first specifying means (Fig. 6: A16) for specifying either one of the data in the formula format displayed on the formula display screen and the data in the graphic format displayed on the graphic display screen; second specifying means (Fig. 6: A20) for, after one of the data in the formula format and the data in the graphic format is specified by the first specifying means, specifying either of the formula display screen and the graphic display screen; graphic form conversion means (Fig. 3: 10) for, when the graphic display screen is specified by the second specifying means after the data in the formula format displayed on the formula display screen is specified by the first specifying means, converting the data in the formula format displayed on the formula display screen into corresponding data in the graphic format; formula form conversion means (Fig. 3: 10) for, when the formula display screen is specified by the second specifying means after the data in the second format displayed on the graphic display screen is specified by the first specifying means, converting the data in the graphic format displayed on the graphic display screen into corresponding data in the formula format; a display section (Fig. 3: 50) for displaying the formula display screen and the graphic display screen; and a tablet (Fig. 3; 30) for detecting a position of a point in a screen of the display section by drag and drop operations of an input pen, and wherein said first specifying means specifies either of the data in the formula format and the data in the graphic format based on the position of the point detected by the tablet while performing the drag operation of the input pen; and said second specifying means specifies either of the formula display screen and the graphic display screen based on the position of the point detected by the tablet while performing the drop operation of the input pen.