To provide a method for manufacturing a polymeric sheet being the cover sheet of a PVA type polarizer having strong adhesive force with the PVA type polarizer and capable of developing stable polarizing characteristics even if allowed to stand for a long time under a high temperature and high humidity condition, and the excellent polymeric sheet obtained by this method.

The polymeric sheet is manufactured by laminating a polymer B layer peelable from a polymeric resin A layer on at least the single surface of the polymeric resin layer A by melt extrusion molding to form a laminate BA or BAB and, after at least one layer B is peeled from the laminate, surface activation treatment is applied to the layer A being in contact with the layer B and further providing a surface coating layer C on the surface activated treatment layer. Surface activation treatment is applied to the surface to be peeled of the polymeric resin layer A from which the laminated polymer layer B is peeled and the surface coating layer C is provided to the surface activation treatment surface.