A 78-year-old woman was found to have a 5-mm nodular lung shadow on surveillance CT after gastric resection for gastric cancer. Eighteen months later, the nodule had increased to 8 mm in diameter. Lung carcinoma or pulmonary metastasis was suspected, and she underwent thoracoscopic partial lung resection. A diagnosis of ciliated muconodular papillary tumor was made. The tumor was composed of pilus cells and goblet cells that showed papillary proliferation in a lepidic growth pattern. There has been no recurrence in the 2 years since surgery. It has characteristics of both benign and malignant tumors but remains poorly characterized. This is rare, being the 38th reported case in Japan.