A synchrotron radiation experiment and a large-scale simulation are indispensable for development new functional rubber materials in recent years. In this series of lectures, I will try to explain about an analysis of structure of filled rubber vulcanizates by cooperation of a synchrotron radiation experiment and a large-scale simulation. In this third article, I will discuss simultaneous measurement experiments of stress strain curve and ultra-small angle x-ray scattering of end-modified styrene butadiene rubber, and a reorganization of filler structure during the stretching and unloading processes by reverse Monte Carlo simulation using these experimental data. Deformation behavior of silica aggregates during elongation reveals to be different between modified and non-modified SBR.