A 70-year-old woman was performed percutaneous coronary intervention at the stenotic lesion of the 1st diagonal branch. Soon after stenting, cardiac tamponade occurred and emergent cardiac surgery was performed. A large epicardial hematoma was observed in the antero-lateral wall that was compressing the distal diagonal branch. The patient died of multi-organ failure 3 days after surgery. An autopsy of her heart revealed an extensive intramural hematoma in the left ventricular wall. There was no evidence of perforation of the stented lesion. The suspected cause was neither coronary perforation nor coronary rupture of target lesion.