Radiotherapy for breast cancer has been performed as adjuvant lymph node irradiation after radical operation, irradiation for chest wall relapse, and palliative treatment for bone, lung and brain metastases. However, attention has been paid to irradiation of the breast as a conservative treatment. The role of radiotherapy in breast conservative treatment is to reduce local relapse after shrinkage of operation, and to enhance the cosmetic outcome. The indications of this treatment, technique of irradiation, effects and side effects of irradiation, and risk of radiation-induced cancer were discussed. In Japan, we have experience with this treatment. Breast conservation treatment and modified mastectomy showed the same results in local control and survival. Sometimes the cure and most cases of relief of complaints are attained for recurrent or advanced breast cancer by radiotherapy. High dose rate brachytherapy by 192-Ir showed high local control of uncontrollable tumor by external irradiation. And hyperthermia combined with radiotherapy is also effective for superficial (less than 3 cm in depth) tumor. Even in patients with lung and or brain metastases, radiotherapy sometimes showed complete remission for years. The standard method of radiotherapy for bone and brain metastases is 30 Gy/2 wks, and the symptom relief rate is over 80%. Oncologists should be made aware of the high complaint relief rate by radiotherapy.