A stress analysis device includes: an imaging element that obtains temperature images over a same time range for a same region of an object; a feature point extractor that extracts a feature point in each of the temperature images; a projection transformer that performs projective transformation on each of the temperature images to align the feature point in the temperature images, and aligns the temperature images with respect to a temperature image being a reference; a pixel rearranger that rearranges a pixel array of each of the temperature images subjected to the projective transformation with respect to a pixel array of the temperature image that is the reference; a stress converter that obtains a stress image by multiplying each of the temperature images after pixel rearrangement by a stress conversion coefficient; and an additional averaging part that obtains an additional averaging stress image by adding and averaging the stress images.