An information processing apparatus comprising: a storage unit configured to store map data files of geographical maps, wherein each of said map data files has a file name comprising a zoom level, an x-direction unit code, and a y-direction unit code; a display control unit (21, 38) configured to display a geographical map; wherein the information processing apparatus is configured to: acquire said zoom level, said x-direction unit code, and said y-direction unit code of a file name of a map file of said map data files; compute an area covered by said map file using longitudes and latitudes of edges of said map file; compute an area covered by a smallest scale map in said map data files based on said area covered by said map file and said zoom level; shift said x-direction unit code and said y-direction unit code by a number of bits corresponding to said zoom level in order to compute a bottom left corner longitude and latitude and a top right corner longitude and latitude of said smallest scale map; compute an area covered by said desired zoom level; compute a desired x-direction unit code by subtracting said bottom left longitude of said smallest scale map from a desired longitude, and dividing based on a desired zoom level; compute a desired y-direction unit code by subtracting said bottom left latitude of said smallest scale map from a desired latitude, and dividing based on said desired zoom level; compute a desired map name based on results of computing said area covered by said desired zoom level, computing said desired x-direction unit code, and computing said desired y-direction unit code; and retrieve and display a geographical map corresponding to said map name. a storage unit configured to store map data files of geographical maps, wherein each of said map data files has a file name comprising a zoom level, an x-direction unit code, and a y-direction unit code; a display control unit (21, 38) configured to display a geographical map; wherein the information processing apparatus is configured to: acquire said zoom level, said x-direction unit code, and said y-direction unit code of a file name of a map file of said map data files; compute an area covered by said map file using longitudes and latitudes of edges of said map file; compute an area covered by a smallest scale map in said map data files based on said area covered by said map file and said zoom level; shift said x-direction unit code and said y-direction unit code by a number of bits corresponding to said zoom level in order to compute a bottom left corner longitude and latitude and a top right corner longitude and latitude of said smallest scale map; compute an area covered by said desired zoom level; compute a desired x-direction unit code by subtracting said bottom left longitude of said smallest scale map from a desired longitude, and dividing based on a desired zoom level; compute a desired y-direction unit code by subtracting said bottom left latitude of said smallest scale map from a desired latitude, and dividing based on said desired zoom level; compute a desired map name based on results of computing said area covered by said desired zoom level, computing said desired x-direction unit code, and computing said desired y-direction unit code; and retrieve and display a geographical map corresponding to said map name. acquire said zoom level, said x-direction unit code, and said y-direction unit code of a file name of a map file of said map data files; compute an area covered by said map file using longitudes and latitudes of edges of said map file; compute an area covered by a smallest scale map in said map data files based on said area covered by said map file and said zoom level; shift said x-direction unit code and said y-direction unit code by a number of bits corresponding to said zoom level in order to compute a bottom left corner longitude and latitude and a top right corner longitude and latitude of said smallest scale map; compute an area covered by said desired zoom level; compute a desired x-direction unit code by subtracting said bottom left longitude of said smallest scale map from a desired longitude, and dividing based on a desired zoom level; compute a desired y-direction unit code by subtracting said bottom left latitude of said smallest scale map from a desired latitude, and dividing based on said desired zoom level; compute a desired map name based on results of computing said area covered by said desired zoom level, computing said desired x-direction unit code, and computing said desired y-direction unit code; and retrieve and display a geographical map corresponding to said map name.