As the results of examination of the defective casting in the three foudrys in Tottori city, the author found the next facts. The rate of the formation of defective casting in two foundrys were several percents, but on one foudry it amounted to 20%. The rate of the formation of defective casting has been subjected to the greater influence of the kinds of casting and the founders than the seasons. The casting defects were caused mainly due to erosion scab, blow, cut, un-convincing missum, insffecient beeding, inclusion, crush, warped casting and broken casting. According to the above facts, the author considered that the subjects of inquiry about this problem are as follows : molding sand, molding method, molding box and the equipment, method of dissolusion, casting method, and method of pouring gate
