The objective of this study was to determine the effect of nitrification inhibitor dicyandiamide (DCD) and urease inhibitor hydroquinone (HQ) on ammonia (NH3) and nitrous oxide (N2O) emission from pig slurry applied to Timothy (Phleum pretense L.)sward. The daily emission of ammonia (NH3) and nitrous oxide (N2O) was monitored for 9 days in three different treatments; 1)control (only pig slurry application), 2) DCD treatment (pig slurry + DCD), and 3) HQ treatment (pig slurry + HQ). Most NH3 emission occurred after 4~5 days in three treatments. Total NH3 emission, expressed as a cumulative amount throughout the measurement time, was 1.33 kg N ha 1 in the control. The DCD and HQ treatment decreased total NH3 emission by 16.3% and 25.1%, respectively, compared to the control. Total N2O emission in the control was 47.1 g N ha 1. The DCD and HQ treatment resulted in a reduction of 67.9% and 41.8% in total N2O emission, respectively, compared to the control. The present study clearly indicated that nitrification and urease inhibitor exhibited positive roles in reducing N losses through NH3 and N2O emission.