A hyperthermostable protease having the amino acid sequence represented by the SEQ ID NO:1 of the Sequence Listing or a sequence derived therefrom by deletion, substitution, insertion or addition of one to several amino acid residues, a gene encoding the hyperthermostable protease, and a process for preparing the protease, aiming at providing by genetic engineering techniques a hyperthermophile protease which is advantageous for industrial use.