When changing a nozzle blade angle by rotating a drive ring, a contact load generated between an inner circumferential surface of the drive ring and an outer circumferential surface of a mount can be reduced, allowing the drive ring to rotate smoothly and reducing the amount of wear and a driving force. It is also possible to reduce an impact force, such as engine vibrations, generated at the drive ring when an external force acts, reducing the risk of damage. A plurality of notches (19) are provided at an inner rim of the drive ring (14), and, among inner circumferential surfaces (14a, 14b, 14c, 14d, 14e, 14f, 14g, and 14h) located between the notches (19), when a driving force for rotating the drive ring (14) is applied, the inner diameters of the inner circumferential surfaces (14e, 14f, 14g, and 14h) where the contact load with the outer circumferential surface of a mount becomes large are made larger than the outer diameter of the outer circumferential surface.