Amylose is a food polysaccharide that constitutes a component of starch. It is expected to be a functional polymer material due to its nontoxicity, biodegradability, and ability to form a regular double helix structure. Although it is not easy to isolate amylose from starch, pure amylose can be synthesized by enzymatic polymerization with glucan phosphorylase [1]. This polymerization requires the presence of maltooligosaccharide primers, and the polymerization proceeds even if one end (reducing end) is modified, because the propagation occurs from the other end (nonreducing end). From this, it is possible to obtain structurally well-defined amylose composite materials by polymerizing from primers immobilized on various functional substrates [2]. It is also possible to construct higher-order structures by forming a double helix from the produced amylose (Fig. 145.1) [3]. Furthermore, the synthesis of nonnatural polysaccharides (amylose analogs) is possible by taking advantage of the weak substrate specificity of the enzyme [4]. Practical composite material development from such enzymatically synthesized amylose and its analog polysaccharides is expected [5].