a method and device for displaying map data and related data and thereby permitting easy enlargement of the scope of the application of map - based data services , wherein additional drawing data for superposing on a map displayed on a screen , and setting data for specifying a map display , are sent and received between different application programs using inter - application exchange in a standard data format . required map data and related data are displayed on the screen using a first application program having a function for converting received additional drawing data and setting data to the aforesaid data format and transmitting it by inter - application exchange , then using a second application program which displays a map on the display screen according to the setting data transmitted by the first application program and displays additional data on the screen map corresponding to the additional drawing data .