Cases of acute myocardial infarction (AMI) that occur during pregnancy or postpartum are rarely reported. Ergot derivatives are known to induce the spasmodic contraction of coronary arteries. Administration of ergot derivatives can cause AMI, even in normal healthy people. In several reported cases, ergot derivatives triggered severe AMI during the postpartum period. Here, we report the case of a forty-year-old woman who was successfully impregnated by artificial fertilization and died after treatment with ergot derivatives. The autopsy revealed AMI with severe coronary atherosclerosis. This is the first case that reports aggravation of pre-existent severe coronary atherosclerosis after postpartum infusion of ergot derivatives.