PURPOSE: To provide a contact lens which prevents wetting, overcomes the trouble when worn and has excellent performance by producing the same of a dextran ester/olefin compd. copolymer obtd. by reaction in the presence or absence of a polymn. initiator.

CONSTITUTION: The raw material dextran ester expressed by the formula (1) is produced by bringing dextran into reaction with a satd. acid and acid anhydride in the presence of an acid catalyst or bringing the same into reaction with a satd. acid, acid anhydride and acid halide in a non-acidic liquid medium under a basic condition. Alkyl ester of α, β-unsatd. acids such as, for example, an acrylic acid and methacrylic acid is used as the polymerizable olefinic compd. expressed by the formula (2). The reaction is caused by putting both compds. into a casting mold from the beginning, adding and dissolving a polymn. initiator thereto and heating the mixture to cause reaction particularly in the case of a mass polymn. method except, for example, a soln. polymn. method, suspension polymn. method and emulsion polymn. method. The resultant powder or granular product is worked by a pressing, injecting, extruding and other suitable forming method to a desired molding.