A leakage voltage detection system can be easily mounted on a ground structure such as an existing street light or a traffic light and can detect a leakage voltage of an electric structure in real time. The leakage voltage detection system includes a sensor node mounted on a ground structure, and an equipment management server that determines a risk of a leakage voltage in the ground structure based on detection voltage information from the sensor node. The sensor node includes an electric field probe that measures a potential difference caused by an electric field detected by electrodes, and a sensor box that detects the potential difference between the electrodes of the electric field probe and transmits the potential difference to the equipment management server as a detection voltage. The equipment management server determines the risk of the leakage voltage where the sensor node is mounted based on the received detection voltage from the sensor node, and outputs information on determination of the risk of the leakage voltage.