To overcome the problem wherein a method using a scintillator and a photoelectron multiplier cannot measure a speed in a minute area and cannot obtain a continuous combustion speed distribution within a combustion face, in a combustion speed measuring method which uses X-rays.

Gunpowder or solid propellant 1 is irradiated with X-rays during combustion, an X-ray image is acquired by a photographic apparatus 4 and analyzed, and the combustion speed distribution is obtained with high spatial resolution.