In a jig for inspecting a device provided with at least a radio frequency signal terminal and an earth terminal, a metal block is formed with a through hole extending in a first direction. A contact probe is inserted into the through hole. The contact probe is provided with a metal pipe extending in the first direction. A plunger is retractably projected from one longitudinal end of the metal pipe to be brought into contact with the radio frequency signal terminal. At least two dielectric ring members are provided on an outer periphery of the metal pipe, and fitted with the through hole while forming a gap between the outer periphery of the metal pipe and an inner wall of the through hole, in order to form a coaxial path in which the contact probe serves as a core conductor and the metal block serves as an external conductor. A diameter of the through hole and a diameter of the dielectric ring members are selected such that the coaxial path has a predetermined impedance relative to the radio signal frequency terminal.