In order to display a digital drawing on a display screen of a terminal device at a scale reduction compliant accurately to actual dimensions, a CPU of a tablet-type terminal device displays drawing data of a digital drawing on a display screen at a predetermined scale reduction. At this time, the CPU references attribute information of the data of the digital drawing, compares it with a display density of the tablet-type terminal device, and displays a design drawing on the display screen at a selected fixed scale reduction. In this configuration, the drawing data at a scale reduction compliant accurately to actual dimensions can be displayed on the display screen of the terminal device. Since the display compliant accurately to the actual dimensions is achieved, a user can measure distances and dimensions by directly using a triangle scale on the display screen.