An impedance measurement jig may include a first contact plate, a second contact plate, a cover plate, a plug, and an analyzer. The first contact plate may make electrical contact with an ESC in a substrate-processing apparatus. The second contact plate may make electrical contact with a focus ring configured to surround the ESC. The cover plate may be configured to cover an upper surface of the substrate-processing apparatus. The plug may be installed at the cover plate to selectively make contact with the first contact plate or the second contact plate. The analyzer may individually apply a power to the first contact plate and the second contact plate through the plug to measure an impedance of the ESC and an impedance of the focus ring. Thus, the impedances of the ESC and the focus ring may be individually measured to inspect the ESC and/or the focus ring.