A coupling portion has one end coupleable to a distal end of a measurement spindle. The measurement spindle is disposed on a gauge inspector and movable in a measurement axis direction. A cylindrical stem is insertable into a gauge holding member to hold the inserted stem. The stem slidably holds a spindle having a distal end on which a contact point of a gauge is disposed. A frame has a first end coupled to a second end of the coupling portion and has a second end to which the gauge holding member is mountable. The gauge holding member is held to the frame such that an axis of the stem runs along the measurement axis direction. As a result, inspection is performed easily and accurately in a reverse posture with a contact point facing upward when a gauge is inspected.