Due to the global worming issue, CO₂ emissions from the use of fossil resources need to be reduced by substitution to renewable resources. In such a background, the use of woody biomass as chemicals and materials is drawing attention, because about 10% of petroleum is currently used for material production. Thermochemical conversion is one of the conversion technologies expected for that purpose. Renewable electricity has multiple options, including solar, wind and geothermal, but biomass is the only renewable carbon source. Therefore, it is important to develop an efficient thermochemical conversion technology that can replace the petrochemical industry. In this presentation, the issues of pyrolysis of woody biomass in the production of low-molecular-weight monomers will be presented from the viewpoint of the molecular mechanism of pyrolysis. Finally, the expected role of the pulp and paper industry in the future will be discussed.