NOVELTY - Methane fermentation (M1) process involves biologically treating the to-be-processed object (I) such as organic waste, organic waste water or their mixtures and generating ammonia from the nitrogen content of the object, prior to the ammonia removal process. Ammonia is removed from (I) after which the mixture is anaerobically treated for methane fermentation.    USE - (M1) is useful for methane fermentation of organic waste, organic waste water or their mixtures (claimed).    ADVANTAGE - In (M1), inhibition of methane fermentation by ammonia is restrained to the minimum. (M1) is efficient and stable. In (M1), by setting temperature conditions in a range lower than solubilized optimal temperature ammonia is produced and high rejection of ammonia is possible.    DETAILED DESCRIPTION - Methane fermentation (M1) after excluding ammonia with high rejection, involves removing ammonia from object (I) to be processed which contains organic waste, organic waste water or their mixtures, and anaerobically treating from which ammonia was removed. Ammonia production is carried out prior to ammonia removal, by providing biological treatment to (I), and producing ammonia from nitrogen content of (I). Optionally, ammonia is produced by fermentation which is done by providing anaerobic treatment in (I), filtration which separates liquid which contains ammonia and the solid content, first methane fermentation process which carries out fermentation of separated liquid, and the second methane fermentation process which carries out fermentation of separated solid content, where (M1) is done by performing high speed fermentation processing by high load of methanation microbe in the first fermentation process.    An INDEPENDENT CLAIM is included for methane fermentation system.    DESCRIPTION OF DRAWING(S) - The figure shows whole methane fermentation system. (Drawing includes non-English language text).    ammonia production tank (1)    ammonia removal apparatus (2)    acid production tank (3)    methane fermentation tank (4)    dehydrator (5)    water treating apparatus (6)