A protective cap is used when a male inner housing to which male terminals and electric wires are attached is passed through a bellows-shaped tubular portion of a grommet. A male outer housing mounted on an annular seal portion of the grommet and the male inner housing accommodated in the male outer housing in a state where the male inner housing accommodates and holds the male terminals connected to the electric wires constitutes the connector. The protective cap includes a circular cap main body having an accommodating recess that accommodates tab portions of the male terminals protruding more than a front face of the male inner housing, at least a front side of the male inner housing being fitted into the accommodating recess. An outer diameter of the cap main body is smaller than an inner diameter of the bellows-shaped tubular portion.