The frequency of generation of multidrug-resistant mutants of Staphylococcus aureus was examined by selection with various antiseptics and fluoroquinolones and the mutated genes were characterized. Multidrug-resistant mutants with mutation of the region between the promoter and structural regions of the norA gene were generated more frequently during selective pressure with antiseptics than during selective pressure with FQs. We also obtained evidence for the existence of at least one other gene related to resistance to antiseptics and fluoroquinolones on the chromosome of S. aureus in addition to norA gene.