A thermophilic bacterium producing the extracellular cellulase was isolated from soybean paste, and the isolate WL-12 has been identified as Bacillus licheniformis on the basis on its 16S rRNA sequence, morphology and biochemical properties. A gene encoding the cellulase of B. licheniformis WL-12 was cloned and its nucleotide sequence was determined. This cellulase gene, designated celA, consisted of 1,551 nucleotides, encoding a polypeptide of 517 amino acid residues. The gene product contained catalytic domain and cellulose binding domain. The deduced amino acid sequence was highly homologous to those of cellulases of B. licheniformis, B. subtilis and B. amytoliquefaciens belonging to the glycosyl hydrolase family 5. When the celA gene was highly expressed using a strong B. subtilis promoter, the extracellular cellulase was produced up to 7.0 units/ml in B. subtilis WB700.