A protective film for polarizers, including a cellulose resin having an acyl substituent with from 2 to 4 carbon atoms and having a degree of acyl substitution of from 2.1 to 2.7, which satisfies 25≦Re≦100 and 50≦Rth≦300 and in which the cellulose resin contributes to expression of at least 40% of the Re in the film.