This paper presents a method which enables raster maps to be used like vector maps in the wed environment and develops a raster map viewer which can be executed in the wed browser. Through the preprocessing process the coordinates attached to each object in the raster map can be used as vector information. The raster map viewer makes the spatial analysis possible using the attribute database connected to the coordinates of each object, This map viewer makes the Web GIS can be constructed at the lower cost because the viewer uses the characteristics of raster map. And the map viewer has merit point of easily developing a component for spatial analysis.