3-Alkyloxy and 3-amino phthalicacidderivatives were found to have metallo-β-lactamase inhibitory activity. Among them, 3-amino phthalicacidderivatives showed both potent activity against metallo-β-lactamase, IMP-1 inhibitory activity and a strong combination effect with biapenem (BIPM), carbapenem antibiotic. In particular, the 4′-hydroxy-piperidine derivative showed strong IMP-1 inhibitory activity