Background: Silicosis is more likely to occur in people working in the mining industry. However, workers suffering from silicosis have recently been reported frequently in other areas. We present a case of silicosis occuring in a 43-year-old man who had worked for 20 years in a workplace producing dental porcelain. Case: The man was admitted to the emergency room with acute chest pain caused by pneumothorax. Chest X-ray indicated numerous small opacities spread over the whole lung field and a large opacity in the right middle lung field. According to ILO classification, the shape of the small opacities was t/s, the profusion rate was 2/3 and the large opacity was classified into the B category. Following this diagnosis of silicosis, the patient’s medical history and work exposure history were examined. According to his medical history, he had undergone closed thoracostomy in 2006 because he had suffered pneumothorax twice (in 2005 and 2006) and his smoking history was 7 pack years. In particular, he had been exposed to silica dust for 20 years in his workplace. Conclusion: Despite the absence of any specific risk factor that caused pneumothorax, the patient suffered this condition three times. All clinical results and the progress of his physical symptoms, including radiologic findings from chest X-ray and computed tomography, clearly supported the diagnosis of silicosis. Except for exposure to silica dust in the workplace, no other risk factors causing silicosis were found. Therefore, he was finally diagnosed as having silicosis caused by exposure to silica dust in the workplace and followed by pneumothorax.