This paper presents a mechanical model of paper showing nonlinear stress-strain relation and its strain rate dependency, which is applicable both to tension and creep of paper.To clarify the mechanical property of paper, at first the model was applied on the experimental results of metal. Then, the property of paper was measured and the difference between paper and metal was obtained. Since the mechanical property of paper is very sensitive to moisture content, the following relation between Young's modulus, E and the moisture content, w was also considered.E=E0e-c1w.The experimental results obtained were as follows.(1) The stress of paper, σ, is expressible as a function of strain γ and strain rate γ by, σ=Fγnγm(2) The comparison in physical property between paper and metal shows that both n and m of paper are larger than those of metal, while F and E of metal are larger than those of paper.The present model and the physical property data of paper were successfully applied to the machine design of an actual high-speed printer.