Atopic dermatitis and bronchial asthma are common diseases in children. We report the development of eosinophilic polyangiitis granulomatosis (EGPA) in a young girl being treated for both atopic dermatitis, diagnosed at 1 year of age, and bronchial asthma, diagnosed at 4 years of age. Her eruption did not result in lichenification and was not fully responsive to corticosteroid ointment. Asthma lightened by treatment of inhalational steroids. Hypereosinophilia was detected at 5 years of age, at least 20% of white blood cells, and 44% at 8 years of age. At 10 years of age, she was diagnosed with anti-neutrophil cytoplasmic antibody-negative EGPA. The diagnosis was based on findings of eosinophil-infiltrating granulomatous vasculitis of the skin accompanied by notable peripheral blood eosinophilia, sinusitis, and pulmonary nodules on radiographic evaluation. Asymptomatic myocardial involvement was also detected utilizing dual perfusion and metabolic scintigraphy with Tl/I-BMIPP, which was relieved by 1-year treatment of glucocorticoid combined with immunosuppressive drugs. EGPA is an extremely rare vasculitis that develops several years after preceding allergic disorders. Pediatric-onset EGPA has a poorer prognosis than adult-onset EGPA, which can be attributed to a high prevalence of cardiac involvement. Therefore, accurate diagnosis is critical for improving prognosis. EGPA should be considered when atypical findings are noted in management of atopic dermatitis and bronchial asthma.