An electrical connector (10) has ground planes (13). Each ground plane (13) crosses counter ground planes (36) of the counter connector (30) so as to make a lattice structure when the counter connector (30) is fitted to the connector (10). The contact section (12C) of a signal terminal (12) of the connector (10) has a plane surface perpendicular to the surface of the corresponding counter contact section (34A) of the counter signal terminal (34), and formed at a flexible elastic arm (12B) in the plane surface. The ground plane (13) has pressure-welding sections (18B) and (20B), which individually elastically contact with the facing inner surfaces of each slit, at a portion to be put into each slit of the counter ground plane (36).