A 19-year-old man was transferred to hospital because of myocarditis with cardiogenic shock. Echocardiography showed a left ventricular ejection fraction of 23.8% and an intermediate amount of pericardial effusion. The patient immediately received an intra-aortic balloon pump and percutaneous cardiopulmonary support. Right ventricular endomyocardial biopsy was performed in the acute phase and showed extensive eosinophilic inflammatory cell infiltration, severe interstitial edema and moderate myocardial necrosis. High-dose corticosteroids were administered. Because the patient's antibody titer against Toxocara canis was high and his symptoms had appeared after eating raw deer meat, the diagnosis was fulminant eosinophilic myocarditis caused by a hypersensitivity reaction to visceral larval migrans. After starting high-dose corticosteroids, the ejection fraction dramatically improved, the eosinophilia decreased and the patient made a full recovery.