To provide a coupling nut capable of overcoming defects in a prior art.

The coupling nut for an electric connector is connectable to the electric connector having an outer conductor surrounded by a jacket. The coupling nut is formed as a cylindrical body with a bore extending between a cable end part and a connector end part. An annular wedge groove at the bore sidewall proximate the cable end part with an inclined wedge surface extends from the bore sidewall at a cable end part side up to a bottom diameter part in the wedge groove. As for the snap ring retained in the wedge groove, a gripping part is formed on the interior surface of that snap ring.