A novel luciferase that is distinct from conventional luciferase has been desired. A luciferase mutant comprising an amino acid sequence in which tyrosine at position of 138 is substituted with another amino acid and at least 3 amino acids selected from the group consisting of isoleucine at position of 90, proline at position of 115, glutamine at position of 124 and asparagine at position of 166 are substituted with other amino acids, in the amino acid sequence of SEQ ID NO: 2.