A waterproof structure for a connector includes a housing retaining terminals and having an opening, a cover closing the opening, and a packing mounted on the cover and sealing between the housing and the cover at the opening. The cover has through holes and projections projecting from an outer surface of the cover. The packing has a body sandwiched between the housing and the cover and locked portions continuous to the body. The locked portion projects from the through hole to an exterior space of the cover toward a direction in which the projection projects, and the locked portion is locked by the projection at least in a direction perpendicular to the direction of projection of the projection.