A 69-year-old man presented with bloody sputum. Chest X-ray showed a trabecular shadow in the right upper lung field. Chest CT showed a bronchial cast shadow in the right B³a, extending along the bronchial bifurcations to the periphery. Impaction of the bronchus was suspected. Sputum cytology was class IIIb. Though bronchoscopic examination did not reveal a tumor or obstruction at the orifice of the right B³a, squamous cell carcinoma was diagnosed by biopsy. Right upper lobectomy was performed. Pathologically, the tumor was diagnosed as moderately differentiated squamous cell carcinoma, measuring 25×20×10 mm in size. The tumor showed intrabronchial branching growth into the peripheral site of the right B³a and neither mucoid nor inflammatory granulation tissue was present. Impaction of the bronchus was made up by the squamous cell carcinoma itself. Lung cancer originating in subsegmental or sub-subsegmental bronchi, showed bronchial cast appearance due to intrabronchial growth is very rare.