Hard X-ray photoelectron spectroscopy (HAXPES) is a powerful tool which can observe chemical states of composite elements, including rubber specimens, from the surface to the internal layer without destruction. Furthermore, utilizing angle-resolved photoelectron spectroscopy (ARPES), the chemical states distribution of the elements in bulk and surface regions can be analyzed. In this report, two studies applied HAXPES and ARPES are introduced. The first part is a direct observation focusing on the buried adhesive interface between rubber and brass plate by using HAXPES and ARPES techniques. The chemical state distribution of sulfur compounds in the interface layer is investigated to clarify the thermal degradation mechanism of the adhesion strength. The second part is a study investigating chemical states and kinetics of sulfur in rubber compound. Density variation of S-C and S-S species with heating time is observed in both bulk and surface regions of rubber specimens to discuss rubber vulcanization process.