The solvent casting effect on the infrared (IR) characteristic absorption bands of stereoregular isotactic poly(acrylonitrile) (PAN) film was studied in comparison with those of an atactic sample. The relative intensity of the IR characteristic bands (D-1230/D-1250) Of PAN film was strongly dependent on the kind of dipolar aprotic solvent used in the film preparation. A higher intensity ratio was obtained when a good solvent such as dimethyl sulfoxide was used, whereas a lower value was obtained when a poor solvent such as malononitrile was used. A linear relationship between the intensity ratio of the IR bands and the dissolution power of nine different kinds of dipolar organic solvents was found. The IR characteristic bands of stereoregular PAN was dependent on not only configuration but also conformation through the difference of the molecular cohesion state in the solvent-cast film. The effect; of configuration and conformation on the IR results was quantitatively studied as a function of the film preparation conditions.