To reduce stress of a wheel hub for retaining a wheel on a vehicle using a wheel nut.

A stress reducing device 10 of the wheel hub 12 includes the circular wheel hub 12 having a fitting portion 15 which forms a plurality of holes 14, and a connector 20 with a screw to be engaged into each of the holes. When tensile force is applied to the connector 20 by the wheel nut L which is connected to the connector 20 by the screw, a maximum tensile stress region is generated in the wheel hub 12. The maximum tensile stress region is formed at a position estranged from an upper part of a hub radius which bisects each hole 14. Other embodiments are related with methods to reduce stress of the wheel hub 12 which retains the wheel on the vehicle using the wheel nut L.