Nitrogen dioxide ($NO_2$), which produced during the process of silage, metal etching, explosives, rocket fuels, welding, and by-product of burning of fossil fuels, is one of major components of air pollutant. Accidental exposure of high level of $NO_2$ produces cough, dyspnea, pulmonary edema which may be delayed $4~12$ hours and, in $2~6$weeks, bronchiolitis obliterans. We experienced a case of acute pulmonary injuny induced by industrial exposure to high level of $NO_2$ during repair of $NO_2$ pipeline in a refinery. A 55-year-old man experienced nausea and severe dyspnea in 6 hours after $NO_2$ inhalation. Initial blood gas examination revealed severe hypoxemia accompanying increased alveolar-arterial O2 difference. Radiological examination showed diffuse ground glass opacities in both lung fields. Clinical symptoms and laboratory findings, including radiological study and pulmonary function test were improved with conservative treatment using inhaled oxygen and bronchodilator. and there was no evidence of bronchial fibrosis and bronchiolitis obliterance in chest high resolution computed tomography performed 6 weeks after exposure. Here, we report a case of $NO_2$ induced acute pulmonary injuny with a brief review of the relevant literature.