Male terminals are respectively provided in terminal attachment portions formed on a flange unit. Female terminals and grommets are provided for a harness. A seal lip portion to be fitted into each of the terminal attachment portions is formed on each of the grommets. In the cylindrical terminal attachment portions the male terminals are individually accommodated while being electrically insulated from each other. The terminal attachment portions are arranged alternately in two rows so that a line segment obtained by connecting the respective centers of openings of the terminal attachment portions is a polygonal line. The openings are arranged to form the Olympic symbol. At a fore-end of each of the terminal attachment portions, slits are provided. Owing to the slits, the opening is likely to be enlarged when the rubber grommet is inserted therethrough. As a result, the placement of the rubber grommet is facilitated.