a flange protrudes from side faces of a housing of a connector attached to a panel , a waterproofing ring being provided next to the flange . the positioning of terminals passing through the housing is regulated by an alignment plate . one end of the alignment plate faces protrusions on the waterproofing ring from the side opposite the flange , thereby preventing the separation of the waterproofing ring from the flange . according to this invention , the alignment plate for correcting the positioning of the terminals is used to prevent the separation of the waterproofing ring without incurring high production costs , and as a consequence the connector can easily be attached to the panel .