This ring rolling mill includes a main roll and a mandrel that are brought close to or separated from each other, and roll a peripheral portion of a ring-shaped body in a radial direction of the ring-shaped body while the ring-shaped body is rotated along its peripheral direction in a state where the peripheral portion of the ring-shaped body is pinched in the radial direction between an outer peripheral surface of the main roll, and an outer peripheral surface of the mandrel. This ring rolling mill further includes a mechanism which inclines and supports the mandrel with respect to the rotation axis of the main roll such that the gap between the outer peripheral surface of the mandrel and the outer peripheral surface of the main roll differs on one side and on the other side as seen in a direction along the rotation axis of the main roll.