Central venous catheterization is well used to provide a large mount of fluid and monitor central venous pressure. However, the procedure accompany various complication including pneumothorax, vascular injury, nerve injury and arrhythmia. To verify correct position of catheter, we checked free regurgitation of blood during catheterization. We experienced a case report of right hemothorax that occurred after right central venous catheterization nevertheless checking correct position by free regurgitation.