Amylose triacetate was synthesized by using enzymatically synthesized amylose. The enzymatically synthesized amylose is a linear 1,4-linked poly-alpha-D-glucose, which does not contain a 1,6-linkage. X-ray crystal structure analysis was carried out for amylose triacetate I. Two left-handed (14/3) helices pass through a unit cell with parameters a = 10.92 Angstrom, b = 18.91 Angstrom, and c (fiber axis) = 53.91 Angstrom and space group P2(1)2(1)2(1). The molecule does not have 14(11) symmetry but only has 2(1) symmetry in the crystal. The up- and down-pointing molecules statistically coexist at a crystal site with the ratio 0.87: 0.13. The conformation of the O6 atom is almost tg, but one gg and one gt conformations are included.