A rhizosphere bacterium having strong chitinolytic activity on 0.5% colloidal chitin-containing agar medium was isolated from soil in Canada. Based on the nucleotide sequence of a conserved segment of a 16S rRNA gene, the bacterium was identified as Bacillus cereus M1K. Chitinase active staining of B. cereus M1K was investigated in 12% SDS-PAGE containing 0.01% glycol chitin as a substrate. Active bands of the chitinase isozymes expressed from B. cereus M1K were observed as three bands (56, 48 and 37 kDa) on SDS-PAGE gel. B. cereus M1K was showed antifungal activity against phytopathogens both Rhizoctonia solani KACC 40111 and Fusarium solani KACC 40384. This study was investigated the ability of B. cereus M1K to induce resistance against R. solani KACC 40111 in cucumber plants. Chitinase of 40 kDa was induced by antagonist B. cereus M1K, and chitinase of 35 and 40 kDa was induced by phytopathogen R. solani KACC 40111. These results indicate that the chitinase produced by B. cereus M1K plays an important role in the biocontrol of soil borne phytopathogen.