A portable multi-lead electrocardiogram device includes a holding case, a signal processing module and three metal contacts. The signal processing module is located in the holding case. The metal contacts are located on an exterior surface of the holding case and are electrically connected to the signal processing module. The metal contacts are respectively a body contact, a left hand contact and a right hand contact. The device can measure the electrical activities of the heart beat from two different directions, which greatly improves detecting capability. Professional 12-lead electrocardiogram can also be performed by multiple times of measuring. This portable device allows patients with history of myocardial infarction to perform electrocardiogram test timely when feeling ill and to seek medical attention early.