PURPOSE: To obtain a cellulose acetate excellent in transparency, filtering characteristics, spinnability, especially heat stability irrespective of a low-grade pulp as a cellulose raw material.

CONSTITUTION: Thus cellulose acetate is a cellulose triacetate in which the sum of mol contents of mannose and xylose in constituent saccharide analysis is equal to or higher than 5%, of the sum of mol contents of glucose, mannose and xylose. The triacetate has 440-480K exothermic peak and 560-600K endothermic peak in thermal analysis in a heating process by DSC.