Novel quinolonecarboxylic acid derivatives represented by general formula (1) which have potent antibacterial effects on gram-positive bacteria, in particular, Propionibacterium acnes, wherein R<；1>； represents hydrogen or a carboxyl-protective group； R<；2>； represents optionally substituted cycloalkyl； R<；3>； represents hydrogen, halogeno, optionally substituted alkyl, alkoxy or alkylthio, optionally protected hydroxy or amino, or nitro； R<；4>； represents optionally substituted alkyl or alkoxy； Z represents halogeno, optionally substituted alkyl, alkenyl, cycloalkyl, alkoxy, alkylthio, amino or pyridin-4-yl or pyridin-3-yl optionally having one or more substituents selected from among optionally substituted hydroxy and amino. <；CHEM>；
