Esters of cellulose derivatives and preparation method thereof

Process for preparing esters of cellulose derivatives the degree of polymerization reduction is suppressed, and to provide ester of thermal fluidity and color tone excellent cellulose derivatives during molding obtained by the production method. Ionic liquids, cellulose derivatives, a process for producing the ester of cellulose derivatives by esterification of cellulose derivative in a mixture of esterifying agent selected, carboxylic acid anhydrides, carboxylic acid halides, from the group consisting of carboxylic acid at least one esterifying agent manufacturing method of esterification of a cellulose derivative, which comprises using a being.