Novel quinolonecarboxylic acid derivatives

Novel compounds of the present invention are repre­sented by the general formula (I) wherein R₁ is hydrogen atom or amino, R₂ is fluorine atom or methoxy, R₃ is hydrogen atom or a lower alkyl having 1 to 3 carbon atoms, and n is 0 or 1. The compounds of the general formula (1) exhibit higher antibacterial activity with fewer side-effects than known quinolone antibiotics such as ofloxacin and norfloxacin. Further, the compounds having the general formula (1) have reduced phototoxicity which normally accompanies 6,8-difluoroquinoline antibiotics.