A method of producing a polarizing film having a high polarizing function. Provided is a method of producing a polarizing film, including the steps of: at least dyeing and stretching a first polyvinyl alcohol of two or more band-like polyvinyl alcohol films in the course of a traveling path while traveling the first polyvinyl alcohol film in a longitudinal direction, and bonding a tail end of the first polyvinyl alcohol resin film to a leading end of a second polyvinyl alcohol resin film to at least dye and stretch the first and second polyvinyl alcohol resin films continuously, wherein the first and second polyvinyl alcohol resin films are arranged with the tail end of the first polyvinyl alcohol resin film and the leading end of the second polyvinyl alcohol resin film being layered, and an interface portion thereof is laser welded to perform the bonding.