PROBLEM TO BE SOLVED: To decompose the org. compd. such as org. chlorine compd. with a relatively inexpensive and small sized device and to increase the utilization efficiency of input energy to the device even in the case that the operation time of the device is short and start and stop of operation of the device are performed many times.
SOLUTION: In the decomposition method, a target 2 consisting of a solid to be treated containing at least org. compd. is housed in a shock wave reflective vessel 1 formed of a material having higher impact impedance than that of the solid to be treated. A high speed flying body 4 is collided with the target 2. In such a way, the org. compd. is decomposed by subjected the target 2 to shock compressing. And also the target 2 is ejected to the outside of the vessel to subject the target 2 to adiabatic expansion, so that the resynthesis of the org. compd. is prevented.