Malignant psoas syndrome (MPS) is caused by malignant infiltration of the psoas muscle and adjacent nerves. Patients with MPS have a combination of pain, both neuropathic and nociceptive, which is often refractory to conventional analgesic therapy. We report the case of a 53-year-old female patient with left MPS caused by the growth of pelvic lymph node metastases from uterine carcinosarcoma. Palliative radiation therapy (RT) to the regional lymph nodes was planned; however, we could not start it because the patient was unable to extend her left hip and stay at rest in the supine position during the RT. We administered epidural analgesia with short-acting local anesthetics 30 min before RT. She could extend her hips despite remaining of pain. We then administered single-shot epidural analgesia just before every RT and were able to perform RT as scheduled. Multimodal approach is needed to manage MPS. In this case, combined oral treatment and epidural analgesia was an effective analgesic therapy for relief of pain due to MPS. Here we report the effective pain management of MPS with repeated single-shot epidural block for palliative RT.