Assuming friction sparks in a vehicle crash, the ignitability of gasoline, light oil and paper by grinding sparks were studied. The temperature of ground sparks elevates from 1323K to 1373K, and that is about 2.1 times of the flash point of gasoline in Kelvin and about 2.6 times of that of light oil. At the present, however, pieces of paper and fuels to be contained are more ignitable than such liquid fuels as gasoline by grinding hot particles. The heat transfer from a hot particle to air was also studied to determine the influence of the particle size on the ignitability of combustible mixtures. Most of ground particles are considered to be about 0. 1mm to 0. 2mm in size, and particles of larger sizes are not likely to be generated by the friction of a vehicle body against the road surface on crash. Therefore it will be rare for the spilt fuel like gasoline or light oil to be ignited by hot particles far from the friction point on vehicle crash. It is more probable that the fuel spilt by the crash to be ignited by the friction surface or particles with a high density near to the friction point.