This study intends to check effects,of air pollutant prevention facilities in bituminous coal-fired power plants on N2O gas emission concentration. Bituminous coal-fired power plants install and operate air pollution prevention facilities to prevent air pollution. The exhaust gases generated by such coal-fired power plants generally pass through a flue gas denitrification facility for removal of nitrogen oxides, a dust collector for removal of suspended matter, and a flue gas desulfurization facility for removal of sulfur oxides, and are emitted through a smokestack. To check the effects of prevention facilities on N2O e mission concentrations, sampling is necessary at the front end and rear end of each prevention facility. Exhaust gases were collected from the front and rear ends of the flue gas denitrification facility (SCR), the rear end of the electric dust collector (EP), and the measurement hole on the smokestack to analyze the concentrations of the gases. According to the results, it was identified where N2O emission concentrations were affected by air pollution prevention facilities. In which air pollutant prevention facilities these differences occurred was-analyzed. N2O emission concentration decreased after flue gases passed the flue gas desulfurization facility (FGD)-in all three power plants. The phenome-non of reduction of N2O emission concentrations by bituminous coal-fired power plant FGD is judged attributable to the effect of CaCO3 used in the FGD.