To develop and provide a new method capable of directly manufacturing a casting without a mold, whereby there is no necessity for preparing, using and keeping a pattern.

Such information as two-dimensional drawings indicating necessary dimensions of the shape X of a product model is replaced with three- dimensional drawings by means of a three-dimensional CAD 1. Data on the shape and dimensions of the product by this information are prepared to processing data CAM. A block body 2 consisting of casting sand 2a manufactured by utilizing a known means and optionally hardened based on the processing data is shaved directly by means of a numerically controlled processing machine 3 according to the processing data so that a clearance shaped after the product is formed in the block body. Molten metal 4 is poured into the clearance and is solidified.