An alkaline protease having an amino acid with one or more amino acid residues selected from among those located at (a) position 63, (b) position 89, (c) position 120, (d) positions 63 and 187, (e) position 226, (f) position 296, (g) position 304 of the amino acid sequence of SEQ ID NO: 1, or at positions corresponding to these positions, are the following amino acid residues, respectively: (a): serine, (b): histidine, (c): arginine, (d): serine,(e): tyrosine, (f): valine, and (g): serine; and a gene encoding the alkaline protease.