To provide a shot peening method capable of exhibiting peening effect, while leaving one part of a surface abnormal layer, without scraping the whole thereof.

A projectile material having a grain diameter more than 0.2 mm and equal or less than 1.0 mm and hardness equal or more than that of the projection-objective material is projected to an intergranular oxide layer, which is generated in a carburized and quenched metal surface, at 30-100 m/s of projecting speed or at 0.1-0.5 MPa of pressure so as to obtain 100-500% of coverage, and the intergranular oxide layer is scraped, leaving the intergranular oxide layer at least 5 μm of thickness.