Central venous catheterization may cause life-threatening complications including pneumothorax and hemothorax. We report a case of multiple trauma complicated with an incidence of hemothorax due to a misplaced central venous catheter. Firstly, the tip of the guide-wire was ruptured in subcutaneous tissue and, secondly, the catheter came out of the vessel and caused hemothorax. During left subclavian catheterization, in this 47-years-old male patient, we could not advance the guide wire forward easily in the first attempt and tried to draw it back. In the second attempt, we inserted a new catheter without any difficulty. The blood gas analyses through the catheter for verification of location revealed its venous nature. After the catheterization, 500 mL hemorrhagic fluid was drained through the ipsilateral chest tube. Control chest X-ray showed that the catheter was in the left hemithorax and a piece of the guide wire was present below the left clavicle. Thorax computerized tomography showed that the catheter entered the thoracic cavity and extended to the paramediastinal region. An emergency surgery was performed to remove the piece of the guide wire and the catheter extending out of the vessel. A common method to check the intravenous insertion of a central catheter into a vein is to verify that the easily drawn blood has the nature of venous blood. This method, however, does not exclude the extravascular placement of the catheter in the presence of ipsilateral hemothorax.