A cellulose acetate according to the present invention has a total degree of acetyl substitution of 0.4 to 1.1 and has a compositional distribution index (CDI) of 3.0 or less, where the CDI is specified by the formula: CDI=(Measured value of half height width of chemical composition)/(Theoretical value of half height width of chemical composition) where the measured value of half height width of chemical composition is a half height width of chemical composition determined by analyzing a cellulose acetate propionate by HPLC, where the cellulose acetate propionate is prepared by propionylating all residual hydroxy groups of the cellulose acetate (sample); and Theoretical value of half height width of chemical composition=2·35482√{square root over (3*DPw*(DS/3)*(1−DS/3))}{square root over (3*DPw*(DS/3)*(1−DS/3))}/DPw  [Math. 1] where DS is the total degree of acetyl substitution; and DPw is a weight-average degree of polymerization determined by a GPC-light scattering method using a cellulose acetate propionate prepared by propionylating all residual hydroxy groups of the cellulose acetate (sample).