PURPOSE: To effectively bleach wood pulp by treating the pulp with lignin peroxidase in the absence of peroxide and in the presence of oxygen.

CONSTITUTION: Bleaching of wood pulp is carried out by treating the wood pulp with at least one lignin peroxidase in the substantial absence of added peroxide and in the presence of oxygen. As the above enzyme, those obtained from crude extracts, filtrates or supernatants of white-rot fungi are preferable, and one obtained from a crude extract. a filtrate or a supernatant of Phanerochaete chrysosporium is more preferable.