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ABSTRACT Quinolone-resistant Campylobacter jejuni have been increasing worldwide. Quinolones exert their antibacterial activity by inhibiting DNA gyrase, but most of the isolates acquire quinolone resistance via an amino acid substitution in the A subunit of DNA gyrase. WQ-3810 is a quinolone antibiotic that has been reported to have high potency even to DNA gyrase with amino acid substitutions in several bacterial species; however, there was no information on C. jejuni. Hence, this study aimed to evaluate the activity of WQ-3810 to inhibit wild-type/mutant DNA gyrases of C. jejuni and the bacterial growth for accessing the potency for the treatment of quinolone-resistant C. jejuni infection. The inhibitory activity of WQ-3810 was assessed and compared with ciprofloxacin and nalidixic acid by calculating the half maximal inhibitory concentration (IC50) against wild-type/mutant DNA gyrases. Next, the minimum inhibitory concentration (MIC) of WQ-3810 and five other quinolones was determined for C. jejuni including quinolone-resistant strains with amino acid substitutions in GyrA. Furthermore, the interaction between WQ-3810 and wild-type/mutant DNA gyrase was speculated using docking simulations. The IC50 of WQ-3810 against wild-type DNA gyrase was 1.03 µg/mL and not different from that of ciprofloxacin. However, those of WQ-3810 against mutant DNA gyrases were much lower than ciprofloxacin. The MICs of WQ-3810 ranged