Acute generalized exanthematous pustulosis (AGEP), one of the severe drug eruptions, is characterized by acute onset of generalized erythematous pustular eruptions without hemorrhage and high fever. A 29-year-old woman, who presented generalized pustulosis lesions including intraoral region and high fever after the use of oral anti-influenza drug for influenza B, was admitted to our hospital. The diagnosis was confirmed by the medical history, clinical findings, and clinical examination such as blood test for infectious disease. The symptoms were improved after withdrawal of anti-influenza drug and topical steroid treatment for pustulosis lesions. There has been no evidence of recurrence after being discharged from hospital.