Herein disclosed is a connection structure including a waterproof sheet disposed in an inner surface of a wire connection section and has an opening section in a position corresponding to a conductor exposed section, in which the waterproof sheet is configured such that a front end of the waterproof sheet is positioned on a front side from a front end of a conductor crimp section and a rear end of the waterproof sheet is positioned on a rear side from a rear end of the cover crimp section.