A displacement detecting device for a structural object is achieved, which is capable of accurately measuring displacement of the structural object. The displacement detecting device 1 includes first and second attitude data calculators 11 and 21, a data extractor 30, and a displacement calculator 40. The first attitude data calculator 11 is disposed at a first position of the structural object, calculates attitude data of the first position by using received positioning signals, and calculates a calculated time point of the attitude data of the first position based on a time of a positioning system. The second attitude data calculator 21 is disposed at a second position of the structural object, calculates attitude data of the second position by using received positioning signals, and calculates a calculated time point of the attitude data of the second position based on the time of the positioning system. The data extractor 30 extracts the attitude data of the first and second positions calculated at the sa
