Provided is a residual stress estimation method and a residual stress estimation device capable of suppressing the number of cut pieces to be collected for measuring inherent strain without deteriorating residual stress estimation accuracy. In a case where it is assumed that the inherent strain is uniformly distributed in one direction in a structure, a user measures residual stress from a cut piece collected in a region in which the inherent strain is uniformly distributed and inputs the measured value to the residual stress estimation device. The residual stress estimation device estimates a two-dimensional inherent strain distribution on an analysis surface perpendicular to the one direction in the structure using the input residual stress measured value, transfers the estimated two-dimensional inherent strain distribution to the one direction, and estimates a three-dimensional inherent strain distribution in the structure.