A straight-shaped hollow spring material is used in a blasting apparatus. The length of the spring material is set to be 1.5 m to 3.5 m, and the inner diameter of the spring material is set to be not more than 10 mmφ (not including 0). In inner surface abrasive blasting for the spring material, first and second blastings are performed. In the first blasting, abrasives are ejected to an opening portion of the spring material and are suctioned from a second opening portion thereof. In the second blasting, the abrasives are ejected to the second opening portion and are suctioned from the opening portion. The ejection pressure, the suction pressure, and the like are appropriately set, so that generation of grinding amount difference between the center portion and both end portions of the inner surface of the spring material can be inhibited.