A housing of a connector has an end face in a perpendicular direction perpendicular to an up-down direction. A side portion of a guide member is apart from the end face of the housing. The end face of the housing, the side portion of the guide member and supporting portions of the guide member form a receiving portion which guides and receives a protruding block of a mating connector. When the connector is mounted on a substrate, the side portion and the supporting portions are apart from the substrate. Outside the end face of the housing in the perpendicular direction and under the side portion and the supporting portions in the up-down direction, a lower space is formed to communicate with the receiving portion. The guide members 16 is not located in the lower spaces 20 at all.