The present invention provides a receptacle connector including: a grounding portion configured to ground a connection object; and a ground connection terminal that is configured to be switchably held in a first state in which the ground connection terminal is electrically separated from the grounding portion, or in a second state in which the ground connection terminal is electrically brought into conduction with the grounding portion. The ground connection terminal is switched between the first state and the second state in operative association with interlining of the plug connector and the fitting portion. In the first state, the grounding terminal and the grounding portion are electrically separated. In the second state, the grounding terminal and the grounding portion are electrically brought into conduction with each other through the ground connection terminal.