Cast film of $alpha$-helical protein fraction isolated from S-carboxymethylated wool keratin (SCMKA) was prepared, and the sorption and diffusion behaviors of Orange II for the SCMKA films were investigated in relation to the $alpha$-$eta$ structural transformation of the keratin by stretching. A little difference in apparent dyeing affinities was observed between the intact cast film (random $alpha$-helical structure) and 200% stretched film (oriented $eta$-structure). On the other hand, the diffusion coefficient for the intact film was much larger than that for 150% stretched film eventhough the activation energies of diffusion were the same. It was concluded from the results that the structural transformation makes no difference on the dyeing affinity, however it does on the diffusion pathway longer by the formation of the oriented crystallite.