Composite fiber of PAN and chitosan was obtained by melt spinning the mixture of PAN/chitosan with diluted acetic acid as a plasticizer. Water plasticizes the PAN and acetic acid plasticizes the chitosan. The fiber showed a porous and fibrillar structure which could be converted easily into pulp-like short fibers by pulping. PAN/chitosan pulp showed much higher dye uptake thant powdery chitosan or activated carbon. It is considered that this better sorption capability of the composite fiber results from the relatively large surface area due to its pulp-like state. However, there was no difference in the sorption of heavy metal ions between composite pulp and powdery chitosan.