A receptacle connector includes a receptacle insulator having an annular outer peripheral wall which defines a fitting recess; receptacle contacts; and a receptacle-side metal fixing member. When a projecting fitting portion of a plug insulator of a plug connector is fitted into the fitting recess, plug contacts of the plug connector come into contact with the receptacle contacts, and the plug connector comes into contact with the receptacle-side metal fixing member. The receptacle-side metal fixing member and the receptacle insulator are integrally formed by insert molding, and the receptacle-side metal fixing member includes a resilient contact portion which is spaced from a surface of the outer peripheral wall on the circumferentially inner side thereof when the resilient contact portion is in a free state.