Acute urethritis and arthritis-dermatitis syndrome after sexual contact are often assumed to be caused by Neisseria gonorrhoeae. We report a case of arthritis-dermatitis syndrome in a 32-year-old man who presented with generalized maculopapular and petechial skin lesions and polyarthritis. Acute urethritis developed 1 week after oro-genital sexual contact with a sex worker about 3 weeks before admission. No pathogen was found on smear of urethral discharge and skin lesions, but Gram-negative diplococci were noted in joint fluid, and blood culture yielded N. meningitidis. His condition improved gradually after repeated arthrocentesis and antibiotic therapy with ceftriaxone followed by ciprofloxacin. Oro-genital contact is a transmission route for N. meningitidis infection manifesting as acute urethritis and arthritis-dermatitis syndrome.