Purpose: The purpose of this study was to clarify the quality of life (QOL) and symptoms of acute radiation damage in patients with breast cancer, who have received radiotherapy. Methods: Targeted patients were 68 breast cancer patients undergoing radiotherapy. We asked the patients to record their symptoms using a symptom diary. The patients' QOL was clarified using the SF-8^TM. The patients' medical records were used for investigating the process of treatment. Results: Main symptoms recorded were fatigue, pain, dermatitis, and itchiness. Fatigue was recorded by 54.4%. Pain was recorded by 69.1%. Itchiness was recorded by 58.8%. The symptom appearance time became clear. The QOL scores in all items for the entire investigation period were lower than the average for healthy Japanese women. The QOL scores increased in four domains. A significant difference was seen in physical functioning (PF), role-functioning physical (RP), general health perception (GH), and mental health (MH). The symptom scores at 3 to 5 weeks after the start of the irradiation and the QOL scores at the completion of the irradiation were negatively correlated for the entire items. Conclusion: The results revealed the symptoms and grade of acute radiation damage and the time at which the damage occurred. We must treat patients, considering when patients will suffer from acute radiation damage. The results also suggested that the QOL score was not adversely affected by radiotherapy. However, there was negative correlation between the symptoms induced by irradiation and the patients' QOL. Therefore, nursing intervention would be necessary to reduce symptoms and improve the QOL of patients undergoing radiotherapy.