To provide a cellulose ester film improved in the reversible variation of retardation value due to moisture variation even in the form of a wide-width film, and to provide a polarizing plate excellent in yield, view angle characteristics and visibility and a liquid crystal display device each using the above film.

A cellulose ester compound is provided, being a product that is obtained by reaction between the corresponding cellulose ester and a compound having a 6-22C aliphatic group and also having in the molecule either one group selected from glycidyl, isocyanate, formyl, vinylsulfone and ethyleneimine groups.