1. The author calculated the main yielding factor of soy bean at all prefectural agricultural experiment stations Japan, the total sum of variety investigated by him amounts to 4500. But he argues here onlyon the main yielding factor. 2. The stem length is min. 20, max. 140, mean 65, σ 21 cm. 3. The per tan yield is min. 0.0, max. 3.0, mean 1.17, σ 0.556 koku. 4. The author made the calorie calculation to compare yielding efficiencies of soy bean and paddy rice and sweet potato each other, and the results are as follows: soy bean 680000±310000 Cal., paddy rice 1570000±320000 Cal. and sweet potato 2920000±10400O Cal. 5. But the soy bean must be considered as protein resource, and the comparison of per tan protein yields are as follows : soy bean 57±27 kg. paddy rice 47±10 kg. and sweet potato 26±9kg. 6. The author also argued about the test weight and a hundred grain weight of soy bean.