A 33-year-old man had a high fever and was given Cefcapene and Oseltamivir without a definite diagnosis of influenza. Three days later an abnormal chest shadow was pointed out. Chest CT revealed ground-glass opacities and air-space consolidation in bilateral lung fields. Although he was given antibiotics, lung infiltrates increased and his symptoms worsened. Therefore, he was transferred to our hospital. Corticosteroid pulse-therapy resulted in prompt improvement of chest infiltrates and his symptoms. The drug-induced lymphocyte stimulating test results indicated 170% of oseltamivir and 150% of cefcapene. Considering the clinical course and laboratory data, this was probably drug-induced lung injury caused by oseltamivir.