PROBLEM TO BE SOLVED : To provide a system for map information with longitude and latitude which instantaneously displays a map including a lot to be appraised in the center so that the price of the appraised lot is immediately determined.SOLUTION : To appraise a specific lot of land, the site of the lot is visited through a navigator using a computerized map inputted to a computer and the longitude and latitude are specified, and data files regarding land prices with longitude and latitude attached, such as a land appraisal result file which is already given longitude and latitude, a land appraisal sample file, a published land file, a prefectural reference land file, and a real estate tax assessment file are prepared. A map of the periphery of the appraised lot prepared by the respective data file is displayed, the appraised lot specified by the longitude and latitude is displayed instantly on the map, and the longitude and latitude information is always kept as an appraised spot file, even if map pictures regarding respective appraisals change, the appraised spot can accurately and instantaneously be displayed with the longitude and latitude.