© 2018, The Japan Society of Ultrasonics in Medicine. To our knowledge, only 15 cases of delayed traumatic hemopericardium resulting from non-penetrating chest trauma have been reported. We present the case of a 63-year-old man with delayed hemopericardium, 2 months after striking the anterior chest on a mailbox when he fell down three steps during a postal delivery. Our case and review of the previously reported cases suggest that some cases might show quite slow progression of blood accumulation. Therefore, careful observation of patients who have experienced blunt trauma of the anterior chest is necessary.