Pulmonary pleomorphic carcinoma (PPC) is a poorly differentiated non-small cell lung carcinoma, including squamous cell carcinoma, adenocarcinoma, or undifferentiated non-small cell lung carcinoma with at least 10% spindle and/or giant cells. Here, we report a case of PPC showing undifferentiated non-small cell lung carcinoma with giant cells. A 71-year-old man with dyspnea underwent right lobectomy because of a mass in the right upper lobe of the lung. A 5.0 × 3.0 × 1.5 cm-sized tumor was identified; microscopically, the tumor composed of undifferentiated large sized tumor cells admixed with syncytial tumor giant cells and emperipoletic giant cells. Immunohistochemically, the tumor cells were reactive for pan-cytokeratin, but negative for P40, thyroid transcription factor 1 (TTF-1), and vimentin. The tumor cells were also positive for 3 clones of programmed death-ligand 1 (PD-L1). The clinical and histologic findings supported the diagnosis of an undifferentiated non-small cell lung carcinoma with giant cells, which is a subtype of pulmonary pleomorphic carcinoma. Unfortunately, after surgery, multifocal lymph node metastasis was identified in radiologic examination. Only palliative chemotherapy was administered to the patient, although he was indicated for immunochemotherapy. Pulmonary pleomorphic carcinoma is known to have a poor prognosis, even in early stages of the disease, therefore, we should be careful in the diagnosis to ensure optimal treatment.