NOVELTY - Resource circulation method, involves grinding agricultural and forestry waste material such as rice straw, saccharifying waste material with sulfuric acid, adding calcium carbonate or calcium oxide to saccharified liquid, and neutralizing the saccharified liquid, simultaneously producing lactic acid or succinic acid by inoculating lactic acid producing microorganism such as Bacillus coagulans, Streptococcus salivarius and Kluyreromyces thermotolerans.    USE - For producing lactic acid and succinic acid biodegradable plastics, and as soil improvement material for recovering salt accumulated soil (all claimed).    ADVANTAGE - The biodegradable plastic can be produced. The waste material treatment can be performed at low cost. The biomass with large quantities of gypsum can be obtained.    DETAILED DESCRIPTION - Resource circulation method, involves grinding agricultural and forestry waste material such as rice straw, wheat bran and scrap wood, carrying out saccharification of waste material with sulfuric acid, adding calcium carbonate or calcium oxide to saccharified liquid, and neutralizing the saccharified liquid, simultaneously producing lactic acid or succinic acid by inoculating lactic acid producing microorganism such as Bacillus coagulans, Streptococcus salivarius and Kluyreromyces thermotolerans, where the biomass residue containing gypsum a large quantities, which is produced by solid-electric separation after neutralization is used as soil improvement material for salt accumulation or as a composting raw material. INDEPENDENT CLAIMS are included for the following: (1) producing organic acid such as lactic acid and succinic acid or ethanol, by using organic acid producing yeast chosen from Saccharomyces cerevisiae, Dekkera bruxellensis, organic acid production filamentous fungi such as Rhizopus oryzae, and lactic acid bacteria such as Lactobacillus; and (2) manufacturing fertilizer, soil improvement material, probiotics, microorganism proteins (SCP), using residue produced after organic acid or ethanol fermentation of liquid portion after solid-liquid separation or fermented liquor.