1. A computer simulation method for a macromolecular material comprising the steps of: defining a coarse-grained model of a macromolecular chain modeled by a plurality of beads; performing a molecular dynamics calculation, using the coarse-grained model disposed in a predetermined virtual space; computing a Rouse parameter of the coarse-grained model; defining an all-atom model of an arbitrary macromolecular chain modeled by a plurality of particle models of respective atoms; performing a molecular dynamics calculation by the computer, using the all-atom model disposed in a predetermined virtual space; computing a Rouse parameter of the all-atom model, wherein the computing of a Rouse parameter of the all-atom model comprises obtaining the entire length of the all-atom model, and the obtaining of the entire length of the all-atom model comprises a step in which the position of a carbon atom of the all-atom model at one end thereof is fixed relatively to the virtual space, a step in which a carbon atom of the all-atom model at the other end thereof is forced to move away from said one end, while performing the molecular dynamics calculation, so that the all-atom model is forcibly stretched, a step in which the forcibly stretched all-atom model is structurally stabilized by performing a calculation according to a molecular mechanics method, and a step in which the distance between said one end and other end of the all-atom model structurally stabilized is computed as the entire length Lf of the all-atom model; converting a unit system employed in the molecular dynamics calculation performed by the use of the coarse-grained model into a unit system employed in the macromolecular chain, using the obtained Rouse parameter of the coarse-grained model and the obtained Rouse parameter of the all-atom model; performing a deformation simulation of the macromolecular material, using a virtual space including the coarse-grained models, to obtain a physical quantity of the macromolecular material; converting the obtained physical quantity into that expressed in the unit system employed in the macromolecular chain; judging if the physical quantity is within an allowable range; and if the physical quantity is outside the allowable range, changing conditions set to the virtual space and the coarse-grained models based on which the deformation simulation is performed, and repeating the performing of the deformation simulation, the converting of the physical quantity, and the judging of the physical quantity; if the physical quantity is within the allowable range, outputting the conditions set to the coarse-grained models and the virtual space and manufacturing the macromolecular material based thereon.