NOVELTY - A processing system of organic waste comprises nitrification processing tank (3) which performs nitrification process, denitrifying processing tank (6) which performs denitrifying process, fermented liquor supply line which makes fermented liquor suppliable to denitrifying processing tank, aerobic state formation part which supplies oxygen in nitrification processing tank, and control part (14) which adjusts supply amount of oxygen supplied to nitrification processing tank.    USE - A processing system of organic waste.    ADVANTAGE - The processing system has simple structure, and reduces discharge in air of high nitrous oxide of warming potential, reduces nitrogen content in methane-fermentation liquid and reduces nitrogen contamination of soil or underground water.    DETAILED DESCRIPTION - A processing system of organic waste comprises nitrification processing tank (3) which receives fermented liquor produced in methane-fermentation tank and performs nitrification process, denitrifying processing tank (6) which receives process liquid of nitrification processing tank and performs denitrifying process, fermented liquor supply line which makes fermented liquor suppliable to denitrifying processing tank from methane-fermentation tank, aerobic state formation part which supplies oxygen in nitrification processing tank, first sensor (12) which calculates oxidation-reduction potential of process liquid in denitrifying processing tank, second sensor (13) which calculates pH of process liquid in denitrifying processing tank, and control part (14) which adjusts supply amount of oxygen supplied to nitrification processing tank. The amount of supplies of fermented liquor sent to denitrifying processing tank from methane-fermentation tank is based on detection result of first sensor and second sensor. An INDEPENDENT CLAIM is included for processing method of organic waste.    DESCRIPTION OF DRAWING(S) - The drawing shows a block diagram of processing system of organic waste. (Drawing includes non-English language text).    Nitrification processing tank (3)    Denitrifying processing tank (6)    First sensor (12)    Second sensor (13)    Control part (14)