A computer-implemented elastic response performance prediction method that predicts an elastic response performance expressing deformation behavior of a rubber product, the elastic response performance prediction method comprising: generating a model of the rubber product, operating an input-output terminal to set a constitutive equation as a framework condition of the rubber product, applying the framework condition to the model of the rubber product, and reconstructing model data of the model, deforming the model under the framework condition and predicting the elastic response performance of the rubber product, wherein the constitutive equation is a constitutive equation that expresses temperature and strain dependence of strain energy or of an elastic modulus of the rubber product, and that incorporates a number of links between cross-linked points in a statistical molecule chain which is expressed using a parameter representing extension crystallization, wherein: a number of links n between the cross-linked points in the statistical molecule chain is expressed by the following Equation: n = α ⋅ 1 − X c ⋅ exp − ε ⋅ β wherein α represents a frequency factor of statistical segment motion, ε represents an activation energy of statistical segment motion, β = 1/RT g wherein R is a gas constant and T g is a glass transition temperature, X c represents a crystallization ratio as a parameter expressing the extension crystallization, and X c is expressed by the following Equation when a material of the rubber product exhibits extension crystallization properties: X c = U 1 − U 0 Δ H 0 = Δ ⁢ U Δ H 0 wherein U 0 represents internal energy in a non-deformed state, U 1 represents internal energy in a deformed state, and ΔH 0 represents entropy of solution when crystals melt. generating a model of the rubber product, operating an input-output terminal to set a constitutive equation as a framework condition of the rubber product, applying the framework condition to the model of the rubber product, and reconstructing model data of the model, deforming the model under the framework condition and predicting the elastic response performance of the rubber product, wherein the constitutive equation is a constitutive equation that expresses temperature and strain dependence of strain energy or of an elastic modulus of the rubber product, and that incorporates a number of links between cross-linked points in a statistical molecule chain which is expressed using a parameter representing extension crystallization, wherein: a number of links n between the cross-linked points in the statistical molecule chain is expressed by the following Equation: n = α ⋅ 1 − X c ⋅ exp − ε ⋅ β wherein α represents a frequency factor of statistical segment motion, ε represents an activation energy of statistical segment motion, β = 1/RT g wherein R is a gas constant and T g is a glass transition temperature, X c represents a crystallization ratio as a parameter expressing the extension crystallization, and X c is expressed by the following Equation when a material of the rubber product exhibits extension crystallization properties: X c = U 1 − U 0 Δ H 0 = Δ ⁢ U Δ H 0 wherein U 0 represents internal energy in a non-deformed state, U 1 represents internal energy in a deformed state, and ΔH 0 represents entropy of solution when crystals melt. a number of links n between the cross-linked points in the statistical molecule chain is expressed by the following Equation: n = α ⋅ 1 − X c ⋅ exp − ε ⋅ β wherein α represents a frequency factor of statistical segment motion, ε represents an activation energy of statistical segment motion, β = 1/RT g wherein R is a gas constant and T g is a glass transition temperature, X c represents a crystallization ratio as a parameter expressing the extension crystallization, and X c is expressed by the following Equation when a material of the rubber product exhibits extension crystallization properties: X c = U 1 − U 0 Δ H 0 = Δ ⁢ U Δ H 0 wherein U 0 represents internal energy in a non-deformed state, U 1 represents internal energy in a deformed state, and ΔH 0 represents entropy of solution when crystals melt.