The separation of the bacteria inhibiting Trichoderma sp. mold, the strain causing blue mold disease that occursfrequently when cultivating mushroom while carrying out the efficient fermentation of mushroom medium, from the growth wasdone. In about 200 strains isolated primarily from fungus garden samples, 6 strains were secondly isolated, which had fast growthrates and a clear zone on the plate medium of SM, AM, and CM. Among the 6 strains isolated, the C-1 strain showed highenzymatic activity of cellulase, amylase, and protease, and strong antibacterial activity for the T. virens and T. harzianum, selectedfinally. The selected C-1 strain was identified as Paenibacillus polymyxaby the result of the identification by Bergey's Manual ofSystematic Bacteriology and the analysis of the nucleotide sequence of 16S rRNA, and named as P. polymyxa CK-1. In reviewingthe growth conditions of the P. polymyxa CK-1 strain, the optimum cultivation temperature was 45oC, and the optimum pH forgrowth was in the range of 6.0~7.0. Appropriate incubation time of P. polymyxa CK-1 for the growth inhibition of the fungus T.virens and T. harzianum was 22 to 36 hours. And the fungal growth was not observed, even when leaving two molds inoculatedon each petri dishes, which were treated with 24 hour culture solution of P. polymyxa CK-1 strain for 10 days. As a result ofstudying the thermal stability of the antagonists produced by the P. polymyxa CK-1 strain, no mycelial growth of the two fungi wasobserved in the test group treated for 20 minutes at 60^oC and 100^oC, but mycelial growth was slightly observed in the test grouptreated for 20 minutes at 121^oC. As aresult of reviewing the impact of the P. polymyxa CK-1 culture medium on mushroommycelial growth, it showed no effect on a variety of mushroom mycelial growth including enoki mushroom and shiitakemushroom.