A connector is provided with a retainer in which a retainer insertion hole is covered and terminal fittings are retained with a large force. The connector has an inner housing 12 fittable into an outer housing 11. A retainer insertion hole 23 is so provided as to extend in a direction normal to the extension of cavities 15. A retainer 40 inserted into this insertion 23 faces rear end surfaces 31B of main portions 31 of terminal fittings 30 to prevent the terminal fittings 30 from coming out. According to this embodiment, since the retainer 40 directly prevents the terminal fittings 30 from coming out, the terminal fittings 30 can be retained with a large force. Further, the retainer insertion hole 23 in the inner housing is covered by the outer housing 11 and therefore is not exposed.