With the advent of throw-away products, the final disposal of such products has become a problem to which considerable attention need be given. For example, the investigation in Japan in 2004 shows the fact that the quantity of production of the diaper increases from 3000 million in 2003 to 3,700 million in 2008. Therefore, in this paper, a new treatment technique for decomposing disposable diapers by microorganisms with cryptomeria chips is proposed. In addition, because a small size disposal system with a temperature controller is expected, the disposal processes of disposable diapers are modeled. The simulations with difference temperature conditions are performed using the models. And then, the relationship between temperature and decomposition rate become clear.