The Natsushima Shell Midden (夏島貝塚, Natsushima kaizuka) is an archaeological site in the Natsushima neighborhood of the city of Yokosuka, Kanagawa Prefecture, in the southern Kantō region of Japan containing a Jōmon period shell midden. It was designated a National Historic Site of Japan in 1972. It was then oldest known shell midden in Japan.