A conductive member has a first face adapted to be mounted on a board on which an inspection circuit is arranged and a second face adapted to be opposed to a device to be inspected. The conductive member being formed with a first through hole having a first diameter and communicating the first face with the second face. A contact probe is provided with a tubular body having a second diameter which is smaller than the first diameter, and a plunger retractably projected from one end of the tubular body. A first retainer is formed with a second through hole and opposing at least the second face of the conductive member so as to communicate the first through hole with the second through hole, so that the contact probe is retained in the conductive member while only the plunger is projected from one end of the second through hole. A second retainer is adapted to retain the one end of the tubular body concentrically with the first through hole.