To effectively utilize grinding waste as a resource by mixing granular iron as aggregate and binder in the pulverized fine grinding waste and forming blocky material.

As the grinding waste, a material produced from the grinding of bearing parts, etc., is used. Since an inexpensive water soluble binder is used in a post-process, in the case of sticking abrasive having oiliness, an oil removal treatment is applied. The grinding waste is made to ≤20 wt.% moisture content by executing dehydrating treatment. Successively, this grinding waste is charged into a pulverize-kneading machine, e.g. a rod mill, and formed as the fine powder. Further, the granular iron being the aggregate and the binder, e.g. starch are changed and kneaded. As the granular iron, the one mixed in slag produced in the steelmaking process, etc., is desirable. To 100 pts.wt. of the granular waste, 11-150 pts.wt. of the granular iron and about 1-5 pts.wt. starch, are used in the external ratio. The kneaded material is charged into a briquetting machine and formed as aggregate. The aggregate is left as it is at a place having good ventilation to execute curing. Thereafter, the screening is executed to use this agglomerate as the raw material for iron-making.