A 57-year-old woman was admitted to our hospital because of a high fever, anemia, and hyperferritinemia. Since a bone marrow examination revealed hemophagocytosis, she was diagnosed with hemophagocytic syndrome (HPS). During treatment of HPS, a heliotrope rash and Gottron's sign appeared with elevated levels of serum aldolase. She also developed heart failure. She was diagnosed with dermatomyositis (DM) and associated myocarditis. Although the administration of glucocorticoids, calcineurin inhibitors, intravenous immunoglobulins, and etoposide ameliorated the clinical findings of DM and cytopenia, the fever and hyperferritinemia remained. The addition of infliximab to glucocorticoids and tacrolimus improved the fever and hyperferritinemia and enabled a reduction in the dose of prednisolone without relapse of the diseases.