The purpose of this research is to explain the pollution control behavior mechanism of the private company. Weanalyzed the countermeasures to check sulfur dioxide of Yahata ironworks in Kitakyushu City as a case study. Inmost of the cases details are not always explained regarding the private company's manufacturing cost and cost forpollution control measures. Therefore, we used some data from the securities report, which are the officiallydeclared materials, and we made the finance model of the Yahata ironworks. We observed a change in the break-even point by the pollution control, and the model explained an influence on the enterprise finance of the pollutionmeasures. We set up the use of low sulfur fuel and production adjustment by the smog alarm announcement as a scenario ofthe pollution control. The influence from the use of low sulfur fuel was smaller than the production adjustment, andit became clear that use of low sulfur fuel was a rational choice to do pollution measures. Furthermore, the systemdesigns, which enterprise follows are the important pollution control measures.