Thermo-mechanical behavior of rubber-like materials is one of the unique characteristics, which gives the additional value to final rubber products, such as energy dissipation, flexibility, friction, heat build-up, fatigue and fracture. This paper shows a constitutive equation, which can consider the thermo-mechanical response of rubber-like materials under deformation. It was compared with the experimental results on the strain dependence of temperature change under deformation. Mechanical response model has long been proposed as a variety of constitutive equations and very successful as an industrial design tool by the benefit from the recent rapid evolution of computer technology. Most of them are described by the stress-strain relationship based rather on the phenomenological models without regard to atomic nature. Hence, we derived the constitutive equation from the molecular model, which was based on fundamental physical principles such as molecular statistical thermodynamics.