To provide a new cellulose acylate film having a negative thickness-direction retardation Rth and to provide a composition useful for producing the film.

The cellulose acylate composition comprises at least one cellulose acylate having an aromatic group-containing acyl group (Substituent A), in which a substitution degree with the substituent A satisfies following relational expressions (I) and (II); and the cellulose acylate film comprises the above composition. Formulae are: formula (I) DSA2+DSA3-DSA60.05; and formula (II) 0.11DSA2+DSA3+DSA60.71, wherein DSA2, DSA3 and DSA6 indicate substitution degrees with Substituent A at the 2-, 3- and 6-positions of the cellulose acrylate, respectively.