The preparative methods of a chitosan-deposited activated carbon was studied with using three kinds of chitosan from crab shells, and its characterization was performed. The specific surface area of the chitosan-deposited activated carbon was greatly decreased as chitosan was dissolved into propionic acid, and it did not depend on the concentration of acetic acid. Also, it became to be constant if agitating the activated carbon over 5 hours into the chitosan-dissolved acid solution, and was considerably decreased at high agitation temperature. The deposit of the chitosan with low molecular weight decreased remarkably the specific surface area of activated carbon even with very low loading, but the chitosan with high molecular weight did not to 10wt% loading. The chitosan was uniformly deposited on activated carbon. The chitosan-deposited activated carbon was stable into acid solution over about pH 5 and below 60 ℃, so it may be used as a adsorbent for removing the pollutants in air and waste water.