The authors report a case of uterine torsion in the second trimester pregnancy with a large leiomyoma. A 28-year-old pregnant woman with a leiomyoma approximately 15 cm in size, was diagnosed with preterm premature rupture of membranes (pPROM) and abruptio placentae at 23 weeks and 0 days of gestation. Because the fetal heart rate pattern was extremely variable and decelerated to lower than 70 bpm before a prolonged deceleration to approximately 80 bpm, an emergency cesarean section was performed. Uterine torsion was identified after the uterine incision was sutured. The uterus was rotated 150 degrees clockwise, and the uterine incision had therefore unfortunately been performed in the back wall of the uterus. Because torsion was suspected to result from an increase in uterine size, the existence of a leiomyoma was viewed as the main cause of uterine torsion in this second trimester of pregnancy. This case indicates that it is important to consider the potential risk of uterine torsion when indicated, especially in cases with a risk of having a large leiomyoma.