Wetland has been known as a major biogenic source of $CH_4$ in globe. In a global scale, the amounts of 55~150 Tg $CH_4$ are released into the atmosphere annually from wetlands; and it accounts for about 21% of total $CH_4$ annual global emission. From August 2010 to August 2011, measurements of major greenhouse gas ($CO_2$, $CH_4$, $N_2O$) emissions were conducted from a freshwater wetland at Kunsan ($35^{circ}56^{prime}38.94^{primeprime}N$, $126^{circ}43^{prime}16.62^{primeprime}E$), Korea by using floating closed static chamber method. Flux measurements for these gases from western coastal tidal flat at Seocheon ($36^{circ}07^{prime}13.85^{primeprime}N$, $126^{circ}35^{prime}43.18^{primeprime}E$), Korea were managed from July 2011 to February 2012 by using closed static chamber method. The average gas fluxes and ranges from freshwater wetland experiment were $0.155{pm}0.29;mg;m^{-2};hr^{-1}$ (-0.054~0.942 $mg;m^{-2};hr^{-1}$) for $CH_4$, $17.30{pm}73.27;mg;m^{-2};hr^{-1}$ (-52.44~261.66 $mg;m^{-2};hr^{-1}$) for $CO_2$, and $0.004{pm}0.01;mg;m^{-2};hr^{-1}$ (-0.02~0.07 $mg;m^{-2};hr^{-1}$) for $N_2O$, respectively. Monthly base flux measurement results revealed that $CH_4$ fluxes during summer months in high water temperature were significantly high, and at least order of one higher than those during other months. The average fluxes and ranges of these greenhouse gases from tidal flat during the experimental period were $0.002{pm}0.08;mg;m^{-2};hr^{-1}$ (-0.16~0.22 $mg;m^{-2};hr^{-1}$) for $CH_4$, $-31.18{pm}75.33;mg;m^{-2};hr^{-1}$ (-298.87~101.93 $mg;m^{-2};hr^{-1}$) for $CO_2$, and $0.001{pm}0.01;mg;m^{-2};hr^{-1}$ (-0.017~0.03 $mg;m^{-2};hr^{-1}$) for $N_2O$, respectively. Comparing the results of gas emissions from tidal flat to those from freshwater wetland, we found significantly lower emissions from tidal flat based on the experiment. Physicochemical parameters of water and soil at these experimental plots were also sampled and analyzed for understanding their correlation with these gas emissions.