Polyporus brumalis has shown resistance to DBP treatment at concentration of 250 µM, and its DBP degradation efficiency was approximately 95% after 12 days of incubation. The addition of DBP was showed the induction of lignin degradation enzyme activities, suggesting that these enzymes are involved in the degradation. We isolated cDNAs of lignin degradation enzymes, six MnPs and two laccase genes, and investigated their expression patterns, which were induced by DBP treatment and deferentially regulated in gene transcription levels in P. brumalis. In order to improve the efficiency of lignin degradation for biotechnological applications, we have developed a homologous over-expression system of a isolated gene using the open reading frame sequence of a laccase cDNA of P. brumalis under the control of the gpd promoter. Protoplasts were isolated from liquid cultured mycelia after treating 0.5% usukizyme and transformation as performed by the REMI method. The transformants were selected from minimal medium containing 50 µgml^-1 hygromycin B and confirmed the insert of the recombinant DNA by PCR. We examined the activity of extracellular laccase activity of transformants by decolorization on dye-plate and oxidation of ο-tolidine in liquid culture medium. The laccase activity of the transformants was higher than that of the wild type. Our transformation system should contribute to the efficient production of the extracellular proteins of P. brumalis, which will be accelerate a degradation of lignin and many recalcitrant xenobiotics.