Cobalt is known as a hard metal used in cement and various household products. Occupational exposure occurs during production of cobalt powder, the processing of hard metals, the polishing of diamonds, and the processing of cobalt alloys. There have been cases of cobalt induced interstitial pneumonitis, occupational asthma, and allergic dermatitis. We report a 21-year-old patient with rhinitis and asthma induced by cobalt in a factory manufacturing diamond-cutter made from hard meta. The patient complained of rhinorrhea, sneezing, and dyspnea 5 months after working in the diamond-cutting industry. Skin prick test and patch test with cobalt (CoCl2) showed negative responses. Bronchoprovocation with CoCl2 showed a early asthmatic response. In conclusion, we report a case of cobalt-induced occupational rhinitis and asthma who worked in a factory manufacturing diamond-cutter. Further studies will be needed to investigate the pathogenesis of bronchoconstriction induced by cobalt.