A housing 10 comprises connector-side transmission-permitting portions 10A that permit the transmission of wave signals in the connector-height direction, a circuit board B comprises board-side transmission-permitting portions B1 that permit the transmission of wave signals in the connector-height direction at locations corresponding to the above-mentioned connector-side transmission-permitting portions 10A when the electrical connector 1 is mounted, and, when a counterpart connector component C is inserted all the way to a normal position, the transmission of wave signals permitted in the process of insertion of the above-mentioned counterpart connector component C becomes blocked by the above-mentioned counterpart connector component C, or alternatively, the transmission of wave signals blocked by the above-mentioned counterpart connector component C in the process of insertion of said counterpart connector component C becomes permissible at the locations of the above-mentioned connector-side transmission-permitting portions 10A and the above-mentioned board-side transmission-permitting portions B1.