A closing-body holding structure comprising: an opening portion that can be provided to a connector housing, and that allows an electric wire (We) to be pulled out from an inside of the connector housing to an outside of the connector housing; a closing body (20, 120) that has an electric wire (We) insertion hole for inserting and passing the electric wire (We) pulled out of a wire outlet of the opening portion, and that closes the wire outlet by being attached to the opening portion; and a protecting member that is tubular, and into and through which the electric wire (We) pulled out of the wire outlet via the electric wire insertion hole (21, 121) is inserted and passed, wherein the closing body (20, 120) includes a housing chamber (22, 122) that houses one end of the protecting member, and an inserted portion (23, 123) that includes the housing chamber (22, 122) and that is inserted into the opening portion, characterized in that the protecting member is capable of extending and contracting entirely in a tubular axial direction of the protecting member, the closing body (20, 120) includes an annular portion (24, 124) around the electric wire insertion hole (21, 121), the annular portion (24, 124) locking, in the tubular axial direction of the protecting member, an end surface of the one end of the protecting member housed inside of the housing chamber (22, 122), and the protecting member makes the end surface of the one end abut against the annular portion (24, 124), and applies a pressing force to the closing body (20, 120) from the end surface by a resilience of the protecting member sustained in a compressed state. an opening portion that can be provided to a connector housing, and that allows an electric wire (We) to be pulled out from an inside of the connector housing to an outside of the connector housing; a closing body (20, 120) that has an electric wire (We) insertion hole for inserting and passing the electric wire (We) pulled out of a wire outlet of the opening portion, and that closes the wire outlet by being attached to the opening portion; and a protecting member that is tubular, and into and through which the electric wire (We) pulled out of the wire outlet via the electric wire insertion hole (21, 121) is inserted and passed, wherein the closing body (20, 120) includes a housing chamber (22, 122) that houses one end of the protecting member, and an inserted portion (23, 123) that includes the housing chamber (22, 122) and that is inserted into the opening portion, characterized in that the protecting member is capable of extending and contracting entirely in a tubular axial direction of the protecting member, the closing body (20, 120) includes an annular portion (24, 124) around the electric wire insertion hole (21, 121), the annular portion (24, 124) locking, in the tubular axial direction of the protecting member, an end surface of the one end of the protecting member housed inside of the housing chamber (22, 122), and the protecting member makes the end surface of the one end abut against the annular portion (24, 124), and applies a pressing force to the closing body (20, 120) from the end surface by a resilience of the protecting member sustained in a compressed state.