A handheld electrocardiographic device for perform an ECG signal acquisition is provided. The ECG device includes at least two electrodes for obtaining ECG signals from a user's skin, an analog signal processing module, an analog/digital converter for digitizing the ECG signals, a processor, which controls the ECG device and processes the ECG signals, a display unit for displaying a processed result of ECG signals and other related information, a memory for data storage, a battery for providing power, at least a contacting interface having at least one of the electrodes mounted thereon, and a detecting unit for sensing a physical condition of the contacting interface, wherein the processor compares the physical condition to a preset criterion, and takes the result as a reference for processing the ECG signals.