NOVELTY - Method of controlling anaerobic treatment process, involves maintaining ratio of volatile organic acid generation rate in methane fermentation type and methane generation rate into 10.0 or less.    USE - For controlling anaerobic treatment process (claimed) of organic waste or waste water.    ADVANTAGE - The method enables controlling anaerobic treatment process, efficiently and stably.    DETAILED DESCRIPTION - Method of controlling anaerobic treatment process, involves (a) maintaining ratio of volatile organic acid generation rate in methane fermentation type and methane generation rate into 10.0 or less, (b) maintaining range of fluctuation of the DNA ratio of concentration of genuine bacteria group and methane formation microorganisms group to (approximately) 20 or less and maintaining range of fluctuation of RNA ratio of concentration to (approximately) 300 or less, (c) suppressing accumulation of acetic acid in inside of the system by maintaining DNA ratio of concentration of methane formation microorganisms Methanosarcina to whole methane formation microorganisms into 0.2 or more and maintaining RNA ratio of concentration into 0.5 or more, (d) maintaining DNA ratio of concentration rate of cellulose decomposer microorganisms JC3 strain and whole genuine bacteria group into 0.025 or more by maintaining the acetic acid accumulation concentration of methane fermentation type to 1 or less gCOD/L, (e) maintaining DNA ratio of concentration rate of acid production microorganisms S1 strain and whole genuine bacteria group into 0.02 or more and maintaining RNA ratio of concentration rate into 0.1 or more by maintaining pH of the souring tank in a methane fermentation type to 6.0-8.0, (f) maintaining RNA and DNA ratio of concentration of various microorganisms groups in methane fermentation microorganisms type to a predetermined range, or (g) maintaining steady acid production and methane formation ability by maintaining RNA to DNA ratio of concentration of the methane formation microorganisms group in a methane-fermentation microorganisms type into 2 or less and maintaining the RNA to DNA ratio of concentration of acid production microorganisms group into 0.5 or more. INDEPENDENT CLAIMS are included for the following: (1) method (M1) of carrying out estimation evaluation of stability of activity of methane fermentation type and fixing condition within system of each microorganism species+ADs- (2) evaluating anaerobic microorganisms activity in the methane fermentation system, involves carrying out comprehensively assay detection of DNA and RNA concentration of genuine bacteria group (Bact) and methane formation microorganisms group (MArch) in methane-fermentation microorganisms system using the PCR method, monitoring DNA and RNA concentration of Bact and MArch with time, and carrying out estimation evaluation of methane formation ability from the relative change of unit DNA of methane formation microorganisms group or methane generation rate per amount of RNA and unit DNA of genuine bacteria group or volatile organic acid generation rate per amount of RNA, or monitoring RNA to DNA ratio of concentration (RNA/DNA) of various microorganism groups is with time using the primer set and detection method as described in the method (M1) and carrying out estimation evaluation of methane formation efficiency and environmental inhibiting factor from the above relative change and (3) anaerobic treatment method, involves controlling stable methane formation ability by maintaining the ratio of DNA concentration and RNA concentration of the various methane formation microorganisms with respect to whole methane formation microorganism group measured by the method (M1) in a fixed range, maintaining steady methane formation ability by maintaining ratio with respect to the RNA concentration of whole methane formation microorganism group of the RNA concentration of each acetic acid utilizable methane formation microorganism in methane fermentation type highly than ratio with respect to the RNA concentration of the whole methane formation microorganism group of the RNA concentration of each hydrogen utilizable methane formation microorganism, or controlling steady methane formation ability by maintaining RNA ratio of concentration of the methane formation microorganism Methanosarcina to the whole methane formation microorganism group measured by the method (M1) into 0.5 or more and RNA ratio of concentration of each hydrogen utilizable methane formation microorganism into 0.5 or less.