Nitrification and denitrification potential were detected in the sediment of Lake Soyang by ^14C-bicarbonate incorporation and acetylene blockage method, respectively. The range of nitrification potential was 0.01∼2.49㎍-N gdwt^-1day^-1 and that of denitrification potential was 0.08∼5.25㎍-N gdwt^-1day^-1. Nitrification potential was showed the highest value at station 4 where organic carbon was rich. It was a high value at station 1 and 2 and was a low value with deep. Denitrification potential was showed the lowest value at station 1 in which organic carbon content was poor and water depth was shallow and was showed the highest value at station 4. Nitrification was correlated positively with NH_4^+-N and denitrification was correlated positively with organic carbon. The inorganic nitrogen reduction was comparatively superior to the inorganic nitrogen oxidation at all stations. So it was assumed to loss of nitrogen source from sediment.