<p>Pyrolysis gas chromatography-mass spectrometry (GC / MS) can reveal more detailed characteristics of the structure of organic matter by changing the pyrolysis temperature. In order to investigate the structure and thermal characteristics of complex organic matter, a method ”Continuous” that performs GC / MS analysis at a series of pyrolysis temperatures by repeatedly using the same sample, and a method that prepares a new sample for each pyrolysis temperature ”Replaced” step heating methods were examined and evaluated. In addition, Fourier transform infrared spectroscopy (FT-IR) analysis was also performed using a heating stage to observe changes in the sample during analysis.The reproducibility of each of the two methods was confirmed. With the ”Replaced” method, it was possible to discriminate fine peaks, and with ”Continuous”, the difference in the detected compounds was remarkable for each pyrolysis temperature. The results of the experiments using FT-IR were in line with the tendency of the compound species detected at each pyrolysis temperature in the GC / MS experiments. Therefore, it was found that performing pyrolysis GC / MS analysis by changing the pyrolysis temperature using both methods is useful for the analysis of the components and thermal properties of complex organic molecules.</p>