An electrical connector (1, 2) includes a base (11, 21) having an upper wall (13, 23), a lower wall (14, 24), a pair of connecting walls (136, 236) connecting the upper and lower wall together, and a slot (12, 22) opening frontwardly for receiving a card (4, 5) between the upper wall and the lower wall, the lower wall protruding to the forefront of the connector and forming a pair of supporting portions (19, 29) before the connecting walls, a plurality of terminals (17, 18, 27, 28) retained in the base (11, 21), and a housing portion (130, 131, 230, 231) defined on the upper wall of the base (11, 21), the housing position (130, 131, 230, 231) receiving a protrusion of other connector stacked on the electrical connector (1, 2).