We herein report the case of a 55 year-old male who underwent pulmonary vein isolation (PVI) for paroxysmal atrial fibrillation. From 8 months after PVI, exertional dyspnea rapidly appeared. When he was referred to our hospital, massive pericardial effusion was observed by transthoracic echography. The pericardiocentesis revealed bloody pericardial effusion, and improved symptoms. Although aortic dissection, autoimmune disease, infection, metastatic pericardial tumor, primary pericardial tumor, and malignant neoplasm were considered as differential diagnosis, the cause of pericardial effusion failed to be found. From these findings, the cause of hemorrhagic pericardial effusion was considered delayed cardiac tamponade induced by PVI performed 8 months earlier.