"The pyridonecarboxylic acid derivative or salt thereof of claim 1 or 3, wherein R5 is a group represented by the following formula (a) or (b): ##STR10## wherein A represents an oxygen atom, sulfur atom or NR9 (wherein R9 represents hydrogen atom or a lower alkyl group), e represents a number from 3 to 5, f represents a number from 1 to 3, g represents a number from 0 to 2, J1, to J2 and J3, which" . . . .