Acute myocardial infarction (AMI) in young patients is very rare, but the incidence has increased over years past at younger ages, likely due to the presence of multiple risk factors. We present the first known case of ST-elevation AMI (STEMI) in a young man. A 22-year-old Japanese man was transferred to our hospital due to suddenly occurred anterior chest pain. An electrocardiogram revealed ST elevation in anteroseptal leads together with reciprocal ST depression in inferior leads. An emergency coronary angiogram was performed, revealing a 100% occlusion at segment 6 of the coronary artery and we established a diagnosis of STEMI. The lesion was expanded to 0% stenosis through plain old balloon angioplasty, after which a third-generation drug-eluting stent was installed there. Afterwards, the patient was discharged on day 17. In this case, a combination of mild six risk factors plus family history of hypertension might lead to this atypical event.