A method of waterproofing a terminal that includes a stopper inserted in one opening of a heat shrinkable tube. The heat shrinkable tube is heat-shrunk in this state to form a cap having a end closure. A fluid thermosetting waterproofing agent is injected into the cap from a second opening. A thermal splice, which is formed from welded strands stripped from a plurality of wire terminals, is inserted and immersed in the thermosetting waterproofing agent. Then, the entire cap is heated and heat-shrunk at a predetermined temperature and the thermosetting waterproofing agent is heat-hardened.