Soybean is one of the organisms largely contributing to our life. Therefore, it is important to know soybean from various aspects. The knowledge and soybean itself will be greatly useful, if they are soundly used. The chapters constituting this book present reviews and researches especially concerning the basis of yield, biomass, and productivity in soybean. Yield, biomass, and productivity in plants are some of the bases for maintaining or improving our ecosystem which includes our life and surrounding environments. Therefore, this book is expected to be useful for many people. Of course, more researches and investigations are important to further gain the knowledge concerning the basis of yield, biomass, and productivity and make them useful for our ecosystem.