A 5 year old girl with ASD was scheduled for open heart surgery. A central venous catheter was placed via the right infraclavicular vein after induction of anesthesia. Thirty minutes after insertion of the catheter, a decrease in arterial pressure and pulse pressure, an increase in heart rate and central venous pressure were observed. Cardiac tamponade was revealed by rapid opening of the chest. Gushing blood out of a hole in the right ventricular free wall was confirmed by pericardiotomy. The hemodynamics were stabilized by blood transfusion and surgical closure of the hole on the ventricle. This perforation was thought to be caused by careless insertion of a relatively stiff central venous catheter.