This research was conducted to evaluate the effect of moisture content on direct landfilling prohibition of organic sludge. Organic sludges with moisture content (MC) of 75 and 85% were filled in two lysimeters. The lysimeters were named as Exp.75 and Exp.85, respectively. LFG of 2,064l was generated greatly for Exp.85, compared to 1,500l for Exp.75. LFG generations in Exp.75 and Exp.85 were 64.1l/kg and 157.1l/kg as dry TS basis, and 113.6l/kg and 266.2l/kg as dry VS basis. Total CH4 generation in LFG for Exp.85 was 1,238l, while 1,050l for Exp.75. H2S of 3~150ppmv was generated from Exp.85, which was 5 times higher than 2~30ppmv from Exp.75. Leachate was not generated from Exp.75 during operation time. However, 420ml of leachate was generated from Exp.85. From the results of gas generation, composition, odorous compounds, and leachate generation, landfilling of organic sludge with high MC was more harmful to the environment in spite of great LFG generation. However, direct landfilling of organic sludges without great difference of MC made a severe odor problem. Therefore, it was thought that current direct landfilling prohibition law for all organic sludge was appropriate.