A body detecting element is buried in the ground together with a body such as a metal body and includes a magnetic member acting as a magnetic core, an antenna coil wound around the magnetic member and a capacitor connected to both the ends of the antenna coil for forming a resonance circuit together with the antenna coil. The antenna coil is mounted on the body integrally therewith through an electromagnetic shield member with the outer peripheral surface thereof confronting the outer surface of the body. A body detecting element includes an RFID circuit connected to the antenna coil and mounted on a body integrally therewith such that the outer peripheral surface of the antenna coil confronts the outer surface of the body through an electromagnetic shield member. Even if the body detecting element is mounted on the body such as the metal pipe integrally therewith, it can accurately detect the body because a resonant frequency and the Q value of the coil are not changed. There is almost no possibility that detecting element is broken or moved even if a body other than the above body is dug.