A 63-year-old female with mitral stenoinsufficiency (stenosis and insufficiency) underwent mitral valve replacement. Under general anesthesia, pulmonary artery catheter (PAC) was inserted via the right internal jugular vein. Because the PAC function was normal in perioperative period we didn't recognize the entrapment of the PAC. But on attempting reposition of catheter in postoperative period, we encountered resistance, and postoperative chest X-ray revealed the catheter formed acute angle near right atrial wall. We suspected entrapment of PAC and decided to repeat sternotomy to release the PAC. We found the PAC encircled in the purse-string suture at the inferior vena cava cannulation site. The PAC was removed without any complications.