Placenta increta during the first trimester of pregnancy is extremely rare. Only a few cases of placenta accreta during the latter half of pregnancy manifesting as a uterine mass have been published. This report describes a case of placenta increta that caused prolonged bleeding after a first-trimester abortion, and was identified by magnetic resonance imaging (MRI) as a heterogeneous mass in the myometrium. This is the first report of a placenta increta detected as a uterine mass after first-trimester dilatation and curettage, and its MRI findings.