Novel thienopyridine-carboxylic acid derivatives, which are shown by the general formula ##STR1## wherein R.sup.1 represents hydrogen or a lower alkyl; R.sup.2 represents hydrogen, a lower alkyl or a halogen; or R.sup.1 and R.sup.2, taken together, may represent an alkylene to form a 5- or 6-membered ring with or without alkyl substituents; each of R.sup.4 and R.sup.5 represents hydrogen or a lower alkyl; and their pharmaceutically acceptable salts obtainable when R.sup.4 is hydrogen, which are useful medicines such as chemotherapeutic agents of bacterial infections.