Method for converting coordinate values of map data

The present invention relates to a method for converting coordinate values of map data, wherein three-dimensional effects are displayed on a screen by converting two-dimensional coordinate object values constituting a map without using a three-dimensional graphic library and an additional storage space. In this method, two-dimensional map data including a reference position are loaded from a storage unit and then moved with respect to the reference position and an affiliated map data viewing sight line; an XY coordinate system is defined and two-dimensional coordinate object values are converted into XY coordinate values; and Y-axis coordinate values obtained through this XY coordinate conversion are converted on a reduced scale at a reduction ratio predetermined according to the Y-axis coordinate values, and X-axis coordinate object values in a digital map with the reduced Y-axis coordinate values are converted on an enlarged or reduced scale according to a predetermined X-axis coordinate value conversion function, thereby displaying the map on the screen with three-dimensional effects.