Totally implantable venous access devices are widely used in pediatric oncology. The authors encountered a 10-year-old boy with implantation of the device at the age of 7 years owing to acute lymphoblastic leukemia. In the recent half-year, the device was not used except for regular heparin flushing. However, hydrothorax occurred when fluid therapy was required from the device during this admission. Thoracoscopic approach showed extravascular migration and intrapleural malposition of the catheter.