It is intended to provide a method whereby a target to be analyzed can be easily decomposed in a micro region and a decomposition apparatus. In the decomposition method of decomposing the target to be analyzed and the decomposition apparatus, the target is allowed to coexist with a microparticle and then the microparticle is put into the high-energy state. Then, the target located in the vicinity of the surface of the microparticle is decomposed due to the energy transfer from the high-energy microparticle toward the target. Thus, the target can be easily decomposed in a micro region.