A 71-year-old male consulted a physician for a chest abnormal shadow detected by mass screening. As computed tomography (CT) revealed a nodular shadow in the left upper lobe, he was referred to our hospital. Positron emission tomography (PET) showed high-level accumulation of fluorodeoxy glucose (FDG) at the same site, and the level of Pro gastrin-releasing peptide(ProGRP) as a tumor marker was high(59.5 pg/ml). The level of ProGRP increased to 83.0 pg/ml 2 months later and the surgery was performed to make a diagnosis, however, historological examination during surgery by both needle biopsy and partial resection showed no malignancy. A final diagnosis of fibrosis associated with anthracosis was made, and neither active inflammation nor neoplastic lesion was not demonstrated. At 2 years and 2 months postoperatively, the level of ProGRP was still high(58.5 pg/ml). Although the high level of ProGRP is well known as a useful marker for the diagnosis of lung small cell carcinoma, some patients with renal dysfunction, pneumonia, interstitial pneumonia, pleurisy, or lung carcinoma that is not small cell carcinoma are also positive for ProGRP. Since the present case showed a mild impairment of renal function, it was suggested that the cause of the high level of ProGRP was other than lung cancer.