An object of the present invention is to provide a cellulose acetate with excellent biodegradability in seawater.
A cellulose acetate having a total degree of acetyl substitution of not greater than 2.7, a ratio τ of a sum of a degree of acetyl substitution at the 2-position and a degree of acetyl substitution at the 3-position to a degree of acetyl substitution at the 6-position in the total degree of acetyl substitution of not less than 2.0, and a sulfate component amount of greater than 20 ppm and not greater than 400 ppm.