The present invention relates to an immunological formulation and a diagnostic kit for cardiac disease using human mitochondrial adenylate kinase isozymes. The present invention provides an immunological formulation and a diagnostic kit for cardiac disease, which are featured by using mitochondrial adenylate kinase isozymes which exist in a myocardiac cell among muscle cells, but not in a skeletal muscular cell, as a diagnostic marker for cardiac disease and which enable more correct and easy diagnosis of cardiac disease.