There is provided a polarizing film that is excellent in optical characteristics, and is excellent in durability and water resistance. A polarizing film according to an embodiment of the present invention includes a polyvinyl alcohol-based resin film having a thickness of 10 μm or less. The polyvinyl alcohol-based resin film has an iodine concentration of 8.5 wt % or more; and the polarizing film has a cross-linking index defined by the below-indicated equation of from 100 to 200. (Cross-linking index)=(Iodine concentration in film)×(Boric acid concentration in film)