Evolved gas analysis / photon ionization mass spectrometer (EGA/PI-MS) was applied to analysis of thermal decomposition and combustion gas products of cigarette. Single photon (10.2eV) was used for PI-MS, which can ionize most of volatile organic compounds (VOCs) without fragmentation. Evolved gas components from cigarettes at elevated temperature up to 1073 K were analyzed in the condition with and without O2. At around 550K, gradual decrease in weight was observed both with and without O2, which was derived from thermal decomposition. In the absence of O2, relatively strong signal of oxygenated hydrocarbons were observed. At around 730 K, rapid decrease in weight was observed in the presence of O2, and aromatic hydrocarbons were observed. VOCs from spontaneous combustion by cigarettes were also analyzed by PI-MS, and furan was strongly observed.