A method of manufacturing a polarizer is provided that makes it possible to virtually simultaneously perform a contact of a hydrophilic polymer film with liquid and stretch of the hydrophilic polymer film in a width direction by a tenter method, or the like, using a small and simple manufacturing equipment. A method of manufacturing a polarizer includes a width direction stretching process for stretching a hydrophilic polymer film 1 in the width direction, which is continuously supplied, by gripping both ends in a width direction thereof with grip means 2 and moving the grip means 2 in a longitudinal direction of the film 1 as well as by bringing the film 1 into contact with liquid and also moving the grip means 2, which grips at least one of both ends in the width direction of the film 1, outwardly in the width direction of the film 1; and a dyeing process for dyeing the film 1 by a dichroic material. In the width direction stretching process, a contact with the liquid is carried out by at least one of spraying and coating of the liquid, and the width direction stretching process is carried out in at least one of the dyeing process and a process other than the dyeing process.