To provide a pre-treatment method for the coating face of a light alloy cast component, enabling to form the uniformly coated face at an edge portion of the light alloy cast component which has a particularly complicated shape, such as a vehicular aluminum wheel disc, and also to provide the light alloy cast component.

The vehicular aluminum wheel disc 10 is fixed into a rockable container 12 with the face having the edge portion 8 turned inside the rockable container 12. The rockable container 12 stores machining materials including at least spherical bodies 16 each having a specific gravity of 2 or greater and a diameter of 5-20 mm. The rockable container 12 is rocked, whereby the machining materials collide with the face having the edge portion 8 of the vehicular aluminum wheel disc 10.