A computer-implemented simulation method for calculating parameters of a Lennard-Jones potential between filler particles in a polymeric material for obtaining a viscosity of the polymeric material by using a computer, the polymeric material being one of rubber, elastomer and resin, the method comprising: a process in which a filler model of each of the filler particles is defined, the filler models having a certain diameter, a process in which a polymer model of each of macromolecular chains of the polymeric material is defined, a process in which the filler models and the polymer models are arranged in a predetermined virtual space, a process in which a free energy in the virtual space is calculated based on a mean field theory, the free energy being a Helmholtz free energy, a process in which, by approximating the free energy to the Lennard-Jones potential, parameters σ LJ and ε LJ of the Lennard-Jones potential are obtained, wherein the process for obtaining the parameter ∈LJ and parameter σLJ comprises a step in which the parameter ∈LJ is obtained from the difference between the maximum value Fm and the minimum value Fs of the free energy, and a step in which the parameter σLJ is obtained from a distance between the filler models abutting each other to calculate the minimum value Fs of the free energy, and a process in which a deformation calculation of the virtual space is performed based on the Navier-Stokes equation and the motion equation by using the obtained parameters_σ LJ and ε LJ in order to obtain the viscosity of the polymeric material including the filler, wherein the deformation calculation is performed until the strain becomes a value in a range of from 1 to 100, the parameters of the Lennard-Jones potential being a parameter ε LJ relating to the strength of a repulsive force exerted between the filler models by the Lennard-Jones potential, and a parameter σ LJ corresponding to the diameter of the filler models, wherein the Flory-Huggins theory is employed as the mean field theory, and a χ parameter employed in the Flory-Huggins theory and relating to an interaction between a filler model and a polymer model is set in a range of from 0.0 to 10.0. a process in which a filler model of each of the filler particles is defined, the filler models having a certain diameter, a process in which a polymer model of each of macromolecular chains of the polymeric material is defined, a process in which the filler models and the polymer models are arranged in a predetermined virtual space, a process in which a free energy in the virtual space is calculated based on a mean field theory, the free energy being a Helmholtz free energy, a process in which, by approximating the free energy to the Lennard-Jones potential, parameters σ LJ and ε LJ of the Lennard-Jones potential are obtained, wherein the process for obtaining the parameter ∈LJ and parameter σLJ comprises a step in which the parameter ∈LJ is obtained from the difference between the maximum value Fm and the minimum value Fs of the free energy, and a step in which the parameter σLJ is obtained from a distance between the filler models abutting each other to calculate the minimum value Fs of the free energy, and a process in which a deformation calculation of the virtual space is performed based on the Navier-Stokes equation and the motion equation by using the obtained parameters_σ LJ and ε LJ in order to obtain the viscosity of the polymeric material including the filler, wherein the deformation calculation is performed until the strain becomes a value in a range of from 1 to 100, the parameters of the Lennard-Jones potential being a parameter ε LJ relating to the strength of a repulsive force exerted between the filler models by the Lennard-Jones potential, and a parameter σ LJ corresponding to the diameter of the filler models, wherein the Flory-Huggins theory is employed as the mean field theory, and a χ parameter employed in the Flory-Huggins theory and relating to an interaction between a filler model and a polymer model is set in a range of from 0.0 to 10.0.