The reported success rate of uterine artery embolization (UAE) for obstetrical hemorrhage is more than 90%. We experienced a case of failed UAE for postpartum hemorrhage, although an embolic particle was found pathologically in the uterine vessels without coagulation. A 42-year-old woman (gravida 7, para 2) with placenta previa had genital bleeding at 35 weeks of gestation, and cesarean section was performed. We immediately added UAE aiming to reduce massive bleeding after the cesarean section, successful embolization of the bilateral uterine arteries and internal iliac arteries were confirmed by angiography regardless the vital sign was recovered with an appropriate amount of transfusion; the massive bleeding recurred after 1 hour of UAE. Hysterectomy was performed and pathological findings of the uterus showed that there was no coagulation in the vessels, which was supposed to be observed by the effect of gelatin sponge. In addition, despite the fact that no coagulation was found, only one gelatin sponge was found in 16 slices of the uterine wall specimens. We speculate that thrombotic materials were caught in vasoconstricted vessels triggered by hypovolemic shock due to acute blood loss, and then the gelatin sponge could be washed out after recovering to normalized circulation status leading to recurrent massive hemorrhage.