TECHNOLOGY FOCUS - BIOTECHNOLOGY - Preferred Method: In (M1), the anaerobic treatment is performed by methane-fermentation. (M1) involves performing fermentation step prior to anaerobic treatment, by introducing cultivation processed material to the fermenting agent. The target object is maintained at 45-65degreesC, and at a pH of 5.3-8.0, preferably 50-60degreesC and at a pH of 6.5-7.5. (M1) further involves measuring the number of cellulose decomposing bacterium that belongs to Clostridium genus, having an optimum growth temperature of 45-65degreesC, capable of decomposing cellulose and having 16S rDNA which has 90% homology to a fully defined 1623 nucleotides (SEQ ID NO: 1) sequences given in the specification and/or having cbhA (cellobiohydrolase A) gene having 80% homology to a fully defined 1109 nucleotides (SEQ ID NO: 2) sequences given in the specification. (M1) involves measuring the amount of the microbe, using cbhA gene of cellulose decomposing bacterium as a target, by using primer pair, performing quantitative PCR, measuring the amount of amplified nucleic acid, and determining the number of microbes based on the measurement value, where the primer is chosen from gggttacggcttatcttgacgag (SEQ ID No: 3), tctaccttgctcacaggaacatcag (SEQ ID No: 4), tcctatgtaacagggtatggtgagc (SEQ ID No: 5) and ttctcgtcaagataagccgtaacc (SEQ ID No: 6) or their homolog sequence. (M1) involves measuring the amount of the microbe, using 16S rRNA gene of cellulose decomposing bacterium as a target, by using primer pair, performing quantitative PCR, measuring the amount of amplified nucleic acid, and determining the number of microbes based on the measurement value, where the primer is chosen from tatcattgggtggcatcac (SEQ ID No: 7) and tatctctacactcgtcaagggatg (SEQ ID No: 8), ggagatgtaaccagcgtcaagc (SEQ ID No: 9) and SEQ ID No: 8, or cgttggagatgtaaccagc (SEQ ID No: 13) and acatctgacttgcttccc (SEQ ID No: 14), or their homologous sequences. (M1) involves measuring the number of microbes, using a labeled probe having the oligonucleotide sequences catctgacttgcttccc (SEQ ID No: 10), ctacactcgtcaagggatg (SEQ ID No: 11), cataccggatttctcctttg (SEQ ID No: 12) or their homologous sequences, hybridizing the probe with the nucleic acid of cellulose decomposing bacterium, and determining the number of microbes based on the signal obtained from the labeled probe that hybridized with the target cellulose decomposing bacteria. Preferred Apparatus: In (I), the anaerobic treatment apparatus is a methane fermentation tank. In (I), fermentation tank is provided prior to the step of providing anaerobic treatment tank, and (I) has a unit for introducing a portion of cultivation processed material to the fermentation tank.