Time-resolved X-ray absorption fine structure (XAFS) spectroscopy measurements were conducted to clarify the difference in the formation behaviors of zinc compounds during vulcanization reaction in rubbers with two different vulcanization systems: efficient vulcanization and conventional vulcanization systems. The changes in the ratio of zinc compounds in sample rubbers with time were estimated from the changes in XAFS spectra during vulcanization processes. The results show that the rates of zinc compound formation and consumption were high when the vulcanization accelerator with high accelerating effects were used, and that the formed zinc compounds and the timing of their formation differed greatly depending on the type of vulcanization accelerator.