PURPOSE: To provide a film for a photographic sensitive material excellent in antistatic performance and transparency, undergoing no deformation during storage and also excellent in curl canceling ability after development.

CONSTITUTION: This film for a photographic sensitive material is a polyethylene-2,6-naphthalate film contg. 0.1-10 pts.wt. sulfonate represented by a formula R-SO3M basing on 100 pts.wt. polyethylene-2,6-naphthalate having ethylene-2,6-naphthalate units as the principal repeating units and this film has ≤3% haze and ≥80°C glass transition temp. In the formula, R is 3-30C alkyl or 7-40% aryl and M is an alkali metal an alkaline earth metal.