A compound represented by the general formula (I) or a salt thereof having a potent antibacterial activity against bacteria that have acquired resistance to quinolones, and a medicament for prophylactic and/or therapeutic treatment of an infectious disease containing the compound or a salt thereof as an active ingredient, as well as a medicament for prophylactic and/or therapeutic treatment of an infectious disease containing a combination of the compound or a salt thereof, and a quinolone.
