Wearables are one of the effective tools that can be affixed to a limb of the number body to monitor personal physiology information anytime and anywhere. Electrocardiography (ECG) is the process of recording the electrical activity of the heart. With lightweight design, wearables are ideal gadgets to measure heart rate, pulse, blood pressure, temperature, etc. With embedded optical sensors, wearables can be used for the collection of ECG information. People can measure blood pressure via pressure sensors. Through the temperature and humidity sensors, abnormality in body temperature can be detected. ECG information is used to determine cardiac electrical activities, which can facilitate the prevention and detection of heart disease. This report provides an overview of the latest development of wearable ECG devices and trend analysis by country, sector and field. Key technologies such as Diagnosis and Identification, Measurement and Inspection, HMI (Human-Machine Interface), and AI (Artificial Intelligence) are also examined in the report. Also included are the insights about opportunities of wearable ECG devices for newcomers.