A train-information transmission/reception system comprising: an electric connector that is, for allowing information transmission/reception apparatuses incorporated in a plurality of vehicles constituting a train to transmit and receive train information in an interconnecting manner via an in-vehicle cable, interposed between the in-vehicle cable and the information transmission/reception apparatus, wherein the in-vehicle cable internally includes a plurality of signal lines that transmit the train information and an electrically-conductive shielded layer surrounding the signal lines, one end of a ground line is connected to the shielded layer, characterized in that, the signal lines are connected to connector pins that are installed in an electrically-conductive connector case, which is a casing of an electric connector with a width in a lateral direction narrower than a width in a longitudinal direction, and that are electrically insulated from the connector case, a casing ground is provided to a casing of the information transmission/reception apparatus, and a plurality of contact pins electrically insulated from the casing of the information transmission/reception apparatus and electrically connected to the connector pins are provided to the casing of the information transmission/reception apparatus, and the other end of the ground line is connected to the connector case in a detachable manner, and the connector case is electrically connected to the casing of the information transmission/reception apparatus in a state where the contact pins and the connector pins are respectively connected to each other, a terminal block is provided on a side surface of the connector case to be interposed between an electrically-conductive terminal provided to the other end of the ground line and the connector case and fixes the terminal by using a fixing member, and the electrically-conductive terminal has the fixing member inserted through at a central portion thereof and is formed in a shape of a flat plate, wherein an opening for introducing the signal lines and the ground line is formed on the connector case, and the terminal block is provided in the connector case at a position near the opening. an electric connector that is, for allowing information transmission/reception apparatuses incorporated in a plurality of vehicles constituting a train to transmit and receive train information in an interconnecting manner via an in-vehicle cable, interposed between the in-vehicle cable and the information transmission/reception apparatus, wherein the in-vehicle cable internally includes a plurality of signal lines that transmit the train information and an electrically-conductive shielded layer surrounding the signal lines, one end of a ground line is connected to the shielded layer, characterized in that, the signal lines are connected to connector pins that are installed in an electrically-conductive connector case, which is a casing of an electric connector with a width in a lateral direction narrower than a width in a longitudinal direction, and that are electrically insulated from the connector case, a casing ground is provided to a casing of the information transmission/reception apparatus, and a plurality of contact pins electrically insulated from the casing of the information transmission/reception apparatus and electrically connected to the connector pins are provided to the casing of the information transmission/reception apparatus, and the other end of the ground line is connected to the connector case in a detachable manner, and the connector case is electrically connected to the casing of the information transmission/reception apparatus in a state where the contact pins and the connector pins are respectively connected to each other, a terminal block is provided on a side surface of the connector case to be interposed between an electrically-conductive terminal provided to the other end of the ground line and the connector case and fixes the terminal by using a fixing member, and the electrically-conductive terminal has the fixing member inserted through at a central portion thereof and is formed in a shape of a flat plate, wherein an opening for introducing the signal lines and the ground line is formed on the connector case, and the terminal block is provided in the connector case at a position near the opening.