The present invention relates to alkaline cellulase variants having an amino acid sequence which exhibits at least 95% homology with the amino acid sequence of SEQ ID NO: 2, wherein said alkaline cellulase variant is mutated to include at least one substitution at (a) position 10, (b) position 16, (c) position 22, (d) position 33, (e) position 39, (f) position 76, (g) position 109, (h) position 242, (i) position 263, (j) position 308, (k) position 462, (l) position 466, (m) position 468, (n) position 552, (o) position 564, or (p) position 608 in SEQ ID NO: 2, or at a position corresponding thereto, wherein said alkaline cellulase variant has alkaline cellulase activity. The present invention also relates to a gene encoding the variant; a vector containing the gene; a transformant containing the vector; and a detergent composition containing the alkaline cellulase variant.