A 68-year-old woman was diagnosed with advanced esophageal cancer with lymph node metastasis, for which she received neoadjuvant chemoradiotherapy. During therapy, she had loss of appetite and weight; therefore, we inserted a nasal feeding tube for her nutrition, after which, she gained weight soon. After therapy, she had a high fever with lymphocytopenia and was diagnosed with cytomegalovirus infection because of significantly high CMV antigenemia. Ganciclovir was administered immediately, and she recovered soon. Two months later, we performed esophagectomy, and she recovered without complications. Immediate diagnosis of CMV infection, ganciclovir administration, and nutrition through a feeding tube were useful for the esophageal cancer patient in this report who had immunosuppression and malnutrition during chemoradiation.