In general, patients with acute myocardial infarction (AMI) have severe stenosis secondary to a superimposed thrombus at the event. Optical coherence tomography (OCT) is a useful imaging tool for patients with AMI. This allows us to identify the site of ruptured plaque, erosion of fibrous cap, and characteristics of stenotic lesion. In this case, we present the difference of the ruptured cavity and obstructed lesion.