An inspection device that inspects a structure with a crack, including: an obtainer that obtains images of the structure captured at mutually different times while the structure is subjected to varying loads; a crack detector that detects a crack on a surface of the structure in each image; a motion estimator that divides each image into blocks having a predetermined size, and derives motion vectors of the blocks based on a positional relation between a position of each block relative to a reference in a first image and a position of each block relative to the reference in a second image, the reference being a tip of the crack detected, the first and second images being included in the images; and an inspector that determines safety of the structure based on a difference between ones of the motion vectors of symmetric positions with respect to the crack.