A 58-year-old man with cervical esophageal cancer and a history of epilepsy was treated with chemoradiotherapy from May of 2013. When tube feeding was initiated due to aspiration pneumonitis, the patient showed a degree of irritability that affected routine staff work and treatment compliance. We attempted to perform supportive care for maladjustment by the notice, the fast, and the tube feeding, but there was no improvement. After we added carbamazepine, primidone, and propericiazine (which had been canceled at the initiation of the tube feeding) to the patient's intravenous phenytoin, the symptoms and treatment compliance improved significantly. We concluded that the causes of the patient's irritability were maladjustment and his epilepsy.