The present invention aims at providing a pharmaceutical composition for the prophylaxis or treatment, irrespective of the kind of virus, of viral myocarditis or viral diseases induced by viral myocarditis, by the treatment or prevention of the onset of cytotoxicity in various organs, and a method of the prophylaxis or treatment. The present invention also relates to a pharmaceutical composition for the prophylaxis or treatment of viral myocarditis or viral diseases induced by viral myocarditis, which contains 2-amino-2-(2-(4-octylphenyl)ethyl)propane-1,3-diol or a pharmacologically acceptable salt thereof as an active ingredient. The present invention further relates to a method for the prophylaxis or treatment of viral myocarditis or viral diseases induced by viral myocarditis, which includes administering an effective amount of the aforementioned compound or a pharmacologically acceptable salt thereof.