We herein report the case of a 31-year-old female with a history of a cesarean delivery with a vertical incision at the anterior wall of the uterus due to chorioamnionitis and uterine myoma at 26 weeks of gestation. Ultrasonography revealed that the placenta was located on the cesarean scar on the anterior wall and the retroplacental clear zone could not be depicted at that site. Based on these findings and the existence of multiple placental lacunae, an antenatal diagnosis of adherence of the placenta was made. An elective cesarean section was performed at 37 weeks of gestation. Because the placenta and the myoma were located on the anterior wall, a lower uterine transverse incision was made. A healthy baby (3,109 g) was born with Apgar scores of 9 at 1 minute and 10 at 5 minutes. The placenta was transparent at the previous cesarean scar and could not be detached at this site. Despite the placental adherence, uterine contraction was good and hemorrhage from the uterine incision was small and controllable. A wedge resection of the previous scar with partial adherence of the placenta was successfully performed. The placenta had pathologically invaded deep into the myometrium without decidua. A pathological diagnosis of placenta increta was made. Our findings suggest that wedge resection of the uterine wall is an effective therapeutic strategy for placental adherence. Placental adherence is commonly associated with placenta previa, and previously published reports regarding the ultrasonographic diagnosis of placental adherence have primarily involved cases with placenta previa. The case presented herein suggests that ultrasonographic findings indicating the high possibility of placental adhesion are important for an accurate diagnosis of this condition in the case of a normally located placenta.