There are provided a substrate film, a laminate, and method of manufacturing a polarizing film. The present application provides a substrate film capable of effectively manufacturing a polarizing film having a thickness of about 10 μm or less, about 8 μm or less, about 7 μm or less, about 6 μm or less, or about 5 μm or less and having an excellent function such as polarization performance, a laminate, and a method of manufacturing the same. According to the invention, it is possible to prevent tearing, curling, or the like from occurring in the elongation process and manufacture a polarizing film by easily elongating a polarization material such as a PVA-based resin.