A three-dimensional displacement measuring method includes: calculating camera parameters of N cameras based on M correction images shot at M viewpoints by cameras including the N cameras, where N is an integer greater than 1 and M is an integer greater than N, the M viewpoints being mutually different; and measuring a displacement over time of a subject caused by vibration of the subject in a three-dimensional space, based on (1) sets of N images and (2) the camera parameters. The N images in each of the sets are generated by the N cameras shooting the subject at the same time, and the sets are generated at different times. The different times are set according to a frequency of the vibration of the subject.