1. A simulation method of a granular material comprising: defining a granular material S which is a simulation target in which a force acting on each grain is expressed by a potential dependent term depending on an interaction potential ϕ between grains and a dissipation term depending on dissipation of energy; renormalization-transforming a physical quantity included in the potential dependent term of a motion equation of each grain of the granular material S so that the form of a Hamiltonian expressed by a kinetic energy of each grain of the granular material S and a potential energy based on the interaction potential ϕ does not change; renormalization-transforming a physical quantity included in the dissipation term so that a rate of change of the potential dependent term and a rate of change of the dissipation term based on the renormalization transformation of the physical quantities become equal to each other; and calculating temporal development of a renormalized granular material S′ by assigning initial values to a position vector and a momentum vector of each grain of the renormalized particulate S′ and by performing numerical integration with respect to a motion equation of each grain with a certain time interval width based on the renormalized physical quantities.