The paper sketches recent attempts to construct three-dimensional maps using personal computers. Three-dirnensinal map has some advantages in the representation of quantitative data. So any simple method to construct it w~ contribute to geographical study and education. Three-dirnensional maps for point data (DTM) have been well studied in physical geography, in human geography it is also important to visualize areal data aggregated in some districts (prism map). The author proposed one simple algorithm to construct prism map for grid type data. The shadow line elimination technique for drawing prism maps on grid type data is simple and has two case configurations essentially (Fig. 5). Using this technique I presents one example of Basic program (PRISM) that is consisted of only 200 statements (Fig. 2). Two outputs of 'PRISM' are presented; Fig. 6 shows sample data output, while Fig. 7 and Fig. 8 show the average hight of commercial buildings in OSAKA city area. Prism maps are especialy effective in the following two cases ; first to illustrate 'hight' attribute in urban area, second to illustrate discontinuously distributed valiables such as popuration in rural area.