Abstract: The inspection apparatus for inspecting performance of a structure such as stator windings of an electric rotating machine of the invention comprises a probe including a measuring element, an arm unit and a cylinder face circumferential moving apparatus. The arm unit has an arm link section supporting the probe (mainly comprising a leading end link assembly and an arm posture keeping mechanism), an arm housing section (mainly comprising a guide rail) regarding driving of this arm link section, and an arm driving mechanism. The arm driving mechanism causes the leading end link assembly to project from the guide rail at an angle toward a measuring position side of the stator windings relative to the axial direction of the rotor unit, while causing the arm link section to travel along the guide rail. The arm posture keeping mechanism is provided with a link wire and a spring, and maintains a straight arm posture of the leading end link assembly after projection from the guide rail.