We herein report a case with uterine corneal rupture that occurred at 28 weeks of gestation. The patient was a 30-year-old primigravida without any history of uterine surgery. She had undergone regular pregnancy check-ups from the first trimester, and a normally located gestational sac had been confirmed by ultrasound at 8 weeks of gestation. She was admitted to our hospital for uterine contractions and genital bleeding at 26 weeks of gestation. On admission, a soft mass was felt by palpation at the left lateral region of the abdomen. An ultrasound examination revealed that the mass protruded from the uterine corneal position and had folded placenta in the mass. Threatened uterine rupture was suspected. At 27 weeks’ gestation, a reticular low echo area (39×24 mm) at the margin of the placenta was visualized. Along with frequent uterine contractions and tenderness of the mass at 28 weeks’ gestation, the low echo area increased at the margin of the placenta. Prolonged deceleration was also observed. A diagnosis of uterine rupture and placental abruption was made, and an emergency cesarean section was performed. The blood loss during the operation was 1065 g. A 1173 g healthy neonate was born with an Apgar score (1/5 min) of 8/9. The bulging lesion at the left corneal position was observed, and the myometrium was noted to be thin and ruptured. Similar to the antenatal diagnosis, a uterine rupture from the corneal position of the placenta was diagnosed. Wedge resection of the ruptured uterus at the corneal position was performed using three-layered sutures. Uterine rupture may occur when the placenta is located abnormally, even in cases at low risk for uterine rupture without a past history or perinatal characteristics.