There are many kind of carbohydrate compound having strong bioactivity. Authors had been reported that natural polysaccharide and olligosaccharide would have novel biological activity by chemical modification. Structure analysis of chemically modified dietary fiber polygalactosamine having NH_2 group on 2nd position by use of molecular force field calculation wsa also reported. In this paper, we described that synthesis and structure analysis of sulfated polysaccharides, such as polygalactosamin and chitosan. Molecurar orbital and semi-empirical molecular orbital methods were used for 3-dimentional graphical mapping of electron density, electrostatic potential (the energy of interaction of a point positive charge with the nuclei of a molecule), and local ionaization potential (a measure of the ease with which electrons are detached from a region of space).