A 31-year-old nulliparous woman with severe diffuse uterine adenomyosis, which replaced nearly the whole uterine myometrium, visited our hospital due to severe dysmenorrhea, menorrhagia, and a desire to have a baby. The patient had a history of two spontaneous abortions. Laparotomic adenomyomectomy with transient occlusion of uterine arteries (TOUA) was performed safely and the patient tried in vitro fertilization and achieved a intrauterine twin pregnancy after recovery time of the operation. At 31+6 weeks of gestation, a male neonate baby weighing 1,620 g and a male neonate baby weighing 1,480 g were born by transverse lower segment cesarean delivery. There was no complication after the operation. The babies were discharged after receiving routine neonatal intensive care for neonatal respiratory distress syndrome. Adenomyomectomy with TOUA technique would be an option for conservative surgical treatment in patients with severe diffuse whole uterine adenomyosis. This is the first report of twin pregnancy after diffuse whole uterine adenomyomectomy with TOUA.