To provide a film for thermal stencil printing base paper which makes both character printing and solid printing clear, which causes no nonuniformity in the thickness of lines of printing, nor nonuniformity in density, wherein wrinkles are hardly brought about in laminating and which is excellent in durability and storage properties.

The film for thermal stencil printing paper is a biaxially oriented polyester film having a thickness of 0.2-7 μm. The melting peak temperature of the film is 180-225°C and the solvent shrinkage stress thereof is 400-1,200 g/mm2, while the average air space thickness (Rp) of the film is 3.0-5.5 μm and the average surface roughness thereof is 65-120 nm.