A waterproof structure includes a first seal portion covering around an electric wire to be inserted into a mounting hole of an object to which the electric wire is mounted, the electric wire having a conductor and an insulation covering the conductor, and the first seal portion being elastic and electrically insulative, a housing provided at an end portion of the electric wire, the housing covering the first seal portion, the housing being made of an insulating resin having higher rigidity than the first seal portion and a second seal portion covering around the electric wire, being provided contiguously with an end portion of the housing, and being elastic and electrically insulative.