PURPOSE: To simplify the work to fit a ring on the circumference of a work on a work pallet after the ring on the ring pallet is held.

CONSTITUTION: A ring fitting device 13 to hold a ring which is loaded on a ring pallet and one side of which is notched is provided with a device body 13a, and a pair of two split parts 21a, 21b provided below the device body 13a in an openable/closable manner in the horizontal direction. The device body 13a is provided with a projected driving part 25 which is abutted on a pair of two split parts 21a, 21b and opens/closes them in a movable manner in the vertical direction. A pair of projections 24a, 24b advancing into a notch of the ring are provided on the tip of a pair of two split parts 21a, 21b. When a pair of two split parts 21a, 21b are opened, a pair of projections 24a, 24b are opened, and expand the notch of the ring to hold the ring. When a pair of two split parts 21a, 21b are closed, the holding of the ring is released.