PURPOSE: To sufficiently suppress distortion in case of quenching an annular body, by a simple method and solid constitution, by inserting a plug having a prescribed outside diameter, into an inside diameter hole of the annular body placed on a horizontal base, positioning it, and after that, elastically pressing the annular body from the upper part, and quenching it.

CONSTITUTION: An annular body W set to a quenching temperature is placed horizontally on a base 1, and a plug 2 is raised by a cylinder 3. It has the same outside diameter as the inside diameter hole of the parts W, or larger outside diameter within a prescribed range, is made to go into the inside diameter hole of the parts W by chamfering 21, and is positioned. Also, when the second pressing device 8 is lowered through a rod 41 by the first pressing device 4, a pressing member 6 is lowered, is brought into abutment on the upper surface of the parts W, is stopped, and after that, the device 8 is compressed, and by its elastic pressing force, the parts W are pressed against on the base 1. Subsequently, a cooling ring 9 is lowered to a position surrounding the parts W, is stopped, and after that, a cooling fluid is sprayed through the side circumferential hole of the member 6, and the parts W are quickly cooled and quenched. Compressed deformation and warping of the parts W in this case can be stopped effectively by the plug 2 and pressing force of the device 8. Subsequently, the plug 2 is drawn out in a state that the parts W remains placed.