Polysaccharides and their related compounds are attracting much attention because of their potential for the applications as new functional materials in many research field such as medicines, pharmaceutics, foods, and cosmetics. Therefore, precision synthesis of new polysaccharides with well-defined structure is being increasingly important. For this purpose, enzymatic method is a very powerful tool because the reaction proceeds with highly stereo- and regiocontrolled manners. This book focuses on advances in the practical synthesis of polysaccharides by the phosphorylase-catalyzed chain-elongation on the basis of the viewpoint of polysaccharide engineering.