Electromagnetic shielding about a part connected with a wiring board is easily and reliably carried out by a simple configuration. An electrically-conductive cover member provided at a mating retaining member of both of electric connectors is provided with a cover contact-point part contacting an electrically-conductive shell of a counterpart connector when the mating retaining member is subjected to a turning operation, and the electrically-conductive cover member is subjected to the turning operation together with the mating retaining member, thereby covering the connection part of the counterpart connector mounted on a wiring board and the wiring board by the electrically-conductive cover member, carrying out electromagnetic shielding with respect to the part connected with the wiring board; and, by forming a ground circuit by grounding the electrically-conductive cover member through the cover contact-point part of the electrically-conductive cover member and the electrically-conductive shell, further good electromagnetic shielding characteristics (shield characteristics) are configured to be obtained.