To provide a means for partially enhancing the mechanical property of a light alloy product.

The tool 1 for working the light alloy product, which has a bag-like vessel 21, a working material 25 stored in the vessel 21, and a mounting means, is used to fix the vessel 21 on a wheel 22 for vehicle to close an opening of the tool 1 for working the light alloy product on a surface of a disc 94 (spoke) of the wheel 22 for vehicle, and to swing the wheel 22 for vehicle fixing the vessel 21 to make the working material 25 collide against the surface of the disc 94 (spoke) of the wheel 22 for vehicle.