A socket for mounting on a substrate includes a terminal exposure part that exposes the plurality of substrate connection terminals of the contacts at lower opposing edges of the socket, and a central part that includes a bottom surface bulging part that protrudes downwardly to define a bottom surface of the socket housing. An insulative contact support board that houses the contacts is housed inside a thickness of the bulging part. A bottom surface of a substrate connection terminal of the contacts supported by the contact support board is exposed at the terminal exposure part. A bottom surface bulging part is inserted into a housing bottom mating hole formed in the connection substrate, and the substrate connection terminal is connected to a pattern terminal provided on the upper surface of an edge of the housing bottom mating hole.