NOVELTY - A methane-fermentation control system comprises biomass introduction pipings (1) which introduce biomass feedstocks which differs in total solid (TS) content, methane-fermentation tank (9) which introduces biomass feedstock mixed in adjustment valve, mixing part (7) which mixes biomass feedstock introduced from biomass introduction pipings and produces biogas by methane fermentation, TS measurement unit which measures total solid of biomass introduced to methane-fermentation tank, and biogas measurement unit which measures biogas obtained by methane-fermentation tank.    USE - A methane-fermentation control system for processing organic waste such as excrements, organic refuse, and food-processing residue.    ADVANTAGE - The system can simultaneously measure biogas concentration, ammonia concentration and VFA concentration, judges state in methane-fermentation tank rapidly, and is controllable.    DETAILED DESCRIPTION - A methane-fermentation control system comprises biomass introduction pipings (1) which introduce biomass feedstocks which differs in TS content, methane fermentation system, methane-fermentation tank (9) which introduces biomass feedstock mixed in adjustment valve, mixing part (7) which mixes biomass feedstock introduced from biomass introduction pipings and produces biogas by methane fermentation, TS measurement unit which measures total solid of biomass introduced to methane-fermentation tank, biogas measurement unit which measures biogas obtained by methane-fermentation tank, volatile fatty acid (VFA) concentration measurement unit which is higher-class than propionic acid, control part (15) where measurement data obtained by ammonia concentration measurement unit and VFA concentration measurement unit is inputted and identifies biomass feedstock of control material based on control table according to inputted data, and propionic acid which measures ammonia concentration measurement unit and volatile fatty acid which measure ammonia component in fermentation residue discharged from methane-fermentation tank. The adjustment valve (6) of identified biomass inlet tube is controlled, and amount of introduction is controlled.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of the methane-fermentation control system. (Drawing includes non-English language text).    Biomass introduction pipings (1)    Adjustment valve (6)    Mixing part (7)    Methane-fermentation tank (9)    Control part (15)