A 25-year-old male presented with pruritic papules over his trunk and extremities. The pruritic eruption had appeared on the arms 5 months before and gradually spread over the trunk. Blood tests showed a white blood cell count of 13 760/microL with 42.2% eosinophils. A skin biopsy from the leg revealed necrotizing vasculitis in the upper dermis with prominent eosinophil infiltration in the dermis and subcutis. Liver dysfunction in accordance with eosinophilia was also seen. The underlying disorder causing the eosinophilia was not detected. We diagnosed this case as hypereosinophilic syndrome. Although systemic corticosteroid therapy using prednisolone was effective, the symptoms recurred during a reduction of prednisolone. The addition of cyclosporine resulted in improvement of his symptoms. Both drugs were successfully tapered without relapsing symptoms. Hypereosinophilic syndrome with cutaneous necrotizing vasculitis is a rare condition, and this case suggests that cyclosporine may be a useful therapeutic adjunct in facilitating steroid tapering.