Intramyocardial dissection hematoma (IDH) is an extremely rare complication of myocardial infarction (MI). Echocardiography is the initial imaging modality for IDH in patients with MI. We reported the case of a 74-year-old patient admitted because of abdominal pain and remarkably increased white cell count. He had anterior-wall MI and underwent percutaneous device intervention 8-months ago, his B-cell acute lymphoblastic leukemia (ALL) was recently diagnosed. Two dimensional echocardiography demonstrated decreased lower-anterior interventricular septum akinesis with the formation of an apical left ventricular aneurysm, and a cavitation with echolucent center formed within the tissue of the apical area was detected. Three-dimensional echocardiography with the true-view effect displayed a clearer image of dissecting flap resembling a sheet of tissue and fibers and bundles in the cavitation suggested dissected myocardium. Compared to the echocardiography performed 3-days ago in his community hospital, the intimal flap with the cavitary lesion in the apical region was newly developed. Therefore, the diagnosis of newly developed IDH was made. Considering hematological malignancy and hemodynamic instability, the patient was managed with conservative pharmacological treatments.