The invention is a film of a vinyl alcohol polymer that contains from 0.01 to 20 mol % of cationic group-containing units and contains from 0.5 to 24 mol % of .alpha.-olefin units having at most 4 carbon atoms. The polyvinyl alcohol film gives polarizing films and polarizer which are resistant to water and have good polarizing properties and which are free from a problem of irregular coloration.