A water blocking structure for an insulation-coated wire includes a heat-shrinkable tubular protective member that is closed at one end by a stopper and that accommodates an intermediate portion of an insulation-coated wire, and a resin material that is accommodated in the tubular member and that penetrates the intermediate portion of the insulation-coated wire, the resin material serving as a water blocking agent. Slit portions are formed in a coating of the insulation-coated wire, and the resin material penetrates the intermediate portion via these slit portions. A coating stripping member with a blade whose cutting edges are directed to the inside of the respective slit portions is contained within the protective member.