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 values of objects constituting a map without using a three-dimensional graphic library and an additional storage space.In the method of the present invention, two-dimensional map data for a certain area including a reference position are loaded from a map data storage unit and then moved with respect to the reference position and a sight line along which the two-dimensional map data are viewed from the reference position; an XY coordinate system with an origin of a central position of the moved two-dimensional map data is defined and coordinate values of objects constituting the two-dimensional map data are converted into coordinate values in the XY coordinate system; and Y-axis coordinate values obtained through the XY coordinate conversion of the two-dimensional map data are converted on a reduced scale at a reduction ratio predetermined according to the Y-axis coordinate values, and X-axis coordinate values of the objects 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 while representing three-dimensional effects.