Three or more attachment pins are arranged on a right lateral surface of a nozzle ring at intervals. All the attachment pins are placed outside support holes in the nozzle ring in radial directions of the nozzle ring. A guide ring is provided across right lateral surfaces of the attachment pins. A first side guide member to support a right lateral surface of a drive ring in away that allows the right lateral surface to be in sliding contact therewith is provided to the right of the guide ring. A second side guide member to support a left lateral surface of the drive ring in a way that allows the left lateral surface to be in sliding contact therewith is provided to the left of the guide ring.