To provide a ring having a simple mechanism for retaining a size adjusting piece in prescribed position, excellent decorativeness due to ease of providing a touch of unity, solidity while it is worn and a high article value.

The ring is furnished with a length adjusting piece 6 of a prescribed length that has a swell in an appropriate portion in the lengthwise direction in the inside perimeter of the ring. the size adjusting piece 6 can be rotated around a pivot 8 attached to the size adjusting piece 6, and can be switch between a non-adjustment mode in which the size adjusting piece 6 is held along the inside perimeter of the ring and an adjustment mode in which the size adjusting piece 6 is held with the swell projecting out from the inside perimeter of the ring, and the size adjusting piece 6 is designed to be held nearly in the same position of the inside perimeter in the non-adjustment mode, and in the adjustment mode.