Gefitinib, an epidermal growth factor receptor tyrosine kinase inhibitor, is effective for patients with non-small cell lung cancer. However, the serious adverse effect of interstitial lung disease has been reported with its use. We present the case of a patient with lung adenocarcinoma with re-challenge gefitinib-induced interstitial lung disease with pleural effusion. The patient was then initially treated for atypical pneumonia and gefitinib was stopped, however re-administration of gefitinib led to the same symptoms re-occurring. The patient recovered from the interstitial lung disease with pleural effusion after steroid therapy. Re-administration of gefitinib should be considered cautiously in patients who have previously developed gefitinib-induced interstitial lung disease.