Objective of this study was to investigate adsorption characteristics of NH4-N to biochar produced from rice hull in respective to mitigation of greenhouse gases. NH4-N concentration was analyzed by UV spectrophotometer. For adsorption experiment of NH4-N to biochar, input amount of biochar was varied from 0.4 to 10 g L-1 with 30 mg L-1 NH4-N solution. Its adsorption characteristic was investigated with application of Langmuir isotherm. Adsorption amount and removal rates of NH4-N were decreased at 53.9% and increased at 20.2% with 10 g L-1 compared to 0.4 g L-1, respectively. The sorption of NH4-N to biochar produced from rice hull was fitted well by a Langmuir model. The largest adsorption amount(qm) and binding strength constant(b) of NH4-N were calculated as 0.4980 mg g-1, and 0.0249 L mg-1, respectively. It was observed that dimensionless constant(RL) was 0.58. It was indicated that biochar produced from rice hull is favorably absorbed NH4-N because this value lie within 0