Abstract: A sign detection device is provided with a plurality of sensors, a data acquisition unit, a calculation unit, and a detection unit. The plurality of sensors are respectively disposed at a plurality of positions of a detection target to measure a physical parameter at each positions. The data acquisition unit is configured to acquire time-series change data of the physical parameters from the plurality of sensors. The calculation unit is configured to calculate dynamic network information representing a time change of a complex network structure including a parameter indicating a correlation between the physical parameters at any two positions of the plurality of positions, on the basis of the time-series change data. The detection unit is configured to detect a sign of sudden change vibration of the detection target, on the basis of the dynamic network information.