Despite the desire to measure the composition and concentration of the microparticles included in a gaseous body sample serving as the measurement target, there is a problem that measurement cannot be performed accurately due to the effect of substances other than the gaseous body sample adsorbing to a trapping body of the analyzing apparatus that traps the microparticles, for example. Therefore, provided is a microparticle composition analyzing apparatus that analyzes composition of microparticles contained in a gaseous body sample, comprising a gas analyzer and a control section that sequentially introduces into the gas analyzer a comparative gas and a sample gas caused by the microparticles generated by irradiating the gaseous body sample with a laser.