A commercially available pectinase which shows chitosanolytic activity was covalently modified with polyalkyleneoxide(PAO)-maleic anhydride(MA) copolymers, and the effects of modification of enzyme on chitosanolytic characteristics, such as initial hydrolysis rate,Michaelis-Menten kinetic parameters, and thermostability, are investigated. Moreover, the time-course of chitosan hydrolysis with modified enzymes was obtained experimentally. Enzymatic characteristics change significantly, depending on the hydrophilicity of the modifier and degree of modification. Even though modification of the enzyme causes a reduction of initial activity in any case, it shows favorable characteristics: an increase in the affinity of enzyme to chitosan, an enhancement of thermostability, and an improvement of reducing sugar production with long-term hydrolysis. Especially when the enzyme is highly modified with a relatively hydrophilic copolymer, AKM-1510, these effect increased significantly.