To provide an insulating connector for water supply preventing stainless steel tube from coming off a box nut, deforming, and water leak from a connection part of a sleeve and the stainless steel tube even if abnormal external force acts on the stainless steel tube.

This connector is comprised of the sleeve 5 made of stainless steel, the box nut 10 made of gun metal, an insulating core 17 made of synthetic resin, and a plain packing 18. The sleeve 5 is attached on a tip part of the stainless steel tube 2 by fluidization expansion method. A tubular guide part 12 extending to a designated length in an axial direction is formed on an end part of the box nut 10 in the stainless steel tube 2 side as one body. External force F acting on the stainless steel tube 2 is borne by the guide part 12 to prevent the stainless. steel tube 2 from coming off the box nut 10. An outer circumference part of a flange part 8 of the sleeve is also covered by a cover part 17' of the insulating core 17.