Massive hemoptysis is respiratory compromise which should be managed as a life-threatening condition. In our case, the bronchial blocker played a role in hemostasis of tracheal bleeding very close to the carina and prevented further spillage into the contralateral lung. Right-sided one-lung isolation in an 87-year-old female, who received cardiopulmonary resuscitation due to myocardial infarction, was requested due to hemoptysis. Right-sided bronchial bleeding was suspected on auscultation, but esophageal and tracheal bleeding due to violent intubation with a stylet was also considered. We attempted one-lung isolation with the bronchial blocker. The bronchial blocker was inadvertently advanced to the left mainstem bronchus, but the inflated balloon of the bronchial blocker compressed the site of bleeding, which was within 1 cm proximal and left posterior to the carina. Tracheal bleeding stopped, and we confirmed that hemostasis was achieved with the balloon of the bronchial blocker using a fiberoptic bronchoscope.