A 66-year-old man admitted to our hospital as a roentgenographically occult lung cancer (ROLC) detected by sputum cytology of class IV. A differential brushing of all branches of the bronchi was performed and squamous cell carcinoma was detected only from the right B8 segmental bronchus. Right lower lobectomy was performed and the microscopic findings of surgical specimen revealed the squamous cell carcinomas were seen at not only B8 bronchus but also B7 bronchus. The frequency of multicentricity of ROLC is reported to be high, and a differential bronchial brushing of all bronchi is a very powerful method to diagnose synchronous multiple lung cancer. However, we failed to detect a cancer lesion of B7 segmental bronchus in this case. Since, the outcomes of surgical treatments for either synchronous or metachronous multiple primary lung cancer are satisfactory, limited surgical treatments might be appropriate as an initial treatment for a ROLC.