A forties year-old female visited our hospital on March 2011, complaining chest discomfort. Computed tomography (CT) revealed a huge mass in the anterior mediastinum combined with multiple masses in the lungs, the uterus and the bone. Since no abnormal shadow had been noticed on the chest radiograph on January 2011,they seemed to have grown very rapidly in a short period. The pathological diagnosis following needle biopsies of mediastinal and uterine cervix tumors was undifferentiated carcinoma of the thymus metastasizing to the uterus. She was also suffering from the pain on the right femur and intermittent hypogastralgia due to metastases to the bone and uterus. Although NSAIDs and oxicodone relieved the pain on the right femur, they could not significantly reduce the hypogastralgia. Judging from the nature of the frightful hypogastralgia, the cause was estimated to be not somatalgia but splanchnodynia. Ritodorine hydrochloride, which was then adnimistered for the purpose of inhibiting the contraction of the uterine, was remarkably effective in reducing the pain. According to the literatures reviewed concerning metastases of the extrapelvic malignant tumors to the uterus, the median survival period after occurrence of metastases was 14 months. This report suggests that the administration of Ritodorine hydrochloride can keep the quality-of-life of these patients without suffering from the pain due to metastatic tumor to the uterus.