We report a rare case of sudden hemorrhage caused by breast cancer. A 70-year-old Japanese woman noted fresh bleeding from her left breast. On physical examination, continuous hemorrhage accompanied by an open cavity was observed in the left breast. Mammography and ultrasonography revealed a well-circumscribed mass, with solid and cystic components, that was highly suggestive of intracystic breast carcinoma with direct skin invasion. Computed tomography and bone scintigraphy showed no distant metastasis. Aspiration biopsy of the lesion showed several clusters of adenocarcinoma cells. Modified radical mastectomy was performed with a presumptive diagnosis of stage III B left breast cancer. Invasive ductal carcinoma without skin invasion was diagnosed histologically. To the best of our knowledge, only 6 other cases of sudden hemorrhage caused by breast cancer without skin invasion have been reported in Japan. We review the literature and discuss the clinical characteristics of this unusual phenomenon.