A measurement device for a ring-shaped assembly that measures relative positions, is provided with: a first contact section that comes into contact with a reference surface that is continuous in the circumferential direction of the ring-shaped member and is capable of sliding in the circumferential direction; a second contact section capable of pressing against an opposing surface that faces an opposite side in the radial direction from the reference surface of the ring-shaped member; a base section that supports the first contact section and the second contact section; a third contact section that comes into contact with a measurement-target part of the assembled member; a connecting section that connects the third contact section and the base section; and a measurement unit that measures a displacement of the third contact section relative to the base section.