We report a case of cerebral infarction with mechanical reperfusion therapy for tumor embolism caused by lung cancer. Case Presentation: The patient was a 72-year-old man. We performed emergency mechanical thrombectomy alone for acute left internal cerebral artery (ICA) occlusion and achieved complete reperfusion at the fifth pass with Trevo 4 × 20 mm. Pathologically, the embolus was diagnosed as squamous cell carcinoma. In chest contrast CT, lung cancer invaded the left atrium and pulmonary vein, diagnosed as tumor embolism by this invading tumor. Conclusion: We experienced a very rare case of tumor embolism caused by lung cancer. Although it was difficult to re-canalize, the strut structure of Trevo and push and fluff technique may have been effective against the hard embolus.