A 76-year-old man presented with an anterior myocardial infarction. Coronary angiography showed 99% stenosis in the left anterior descending artery and total occlusion in the left circumflex artery (LCX). After successful percutaneus coronary intervention (PCI) for segment 7, a staged PCI to the LCX with a distal protection system was attempted, but the wire entered the subintima, creating a large dissection and intramural hematoma. Three sirolimus-eluting stents (SES) were implanted to cover the entire hematoma, but 2 weeks later intravascular ultrasound revealed stent malapposition, with healing of the residual hematoma, and vessel enlargement. Optical coherence tomography (OCT) showed the malapposition more clearly. Balloon dilatation successfully achieved apposition of the SES to the vessel wall, but 6 months later it revealed recurrence of malapposition, with the struts covered by thrombus-like tissue. This case suggests that SES implantation treatment of a long intramural hematoma can potentially cause late malapposition because of persistent vessel enlargement related to arterial wall injury and inhibition of neointimal hyperplasia by the SES. OCT is useful in showing the precise condition of the stent struts.