We present a fire investigation method for carpets by analyzing the carbide pattern and oil vapor. The combustion of carpets is dominated by laminar and turbulent flow, and the combustion pattern on the floor surface is shaped like a halo pattern. The combustion pattern on flooring material sprayed with an flammable liquid takes a donut-shaped and a circular pattern in which the core is burned. Surface analysis by substance microscopy showed that the boundary surface was melting and recombining, regardless of whether or not the carpet was treated with flame retardant. In the analysis of the capture of oil vapor using a gas detector tube after combustion was completed, the general carpet was discolored to dark green with one to two divisions, and combustion of ordinary carpets and gasoline exhibited two to three divisions. It was found that one to two divisions of flameproof carpets were discolored to dark green, and combustion of flameproof carpets and gasoline produces five to six divisions. The differences in combustion products could not be clearly distinguished using gas chromatography and mass spectrometry (GC & MS), but the strengths of their response patterns were found to be different.