1. A method for analyzing a phase distribution of a fringe image that calculates a phase distribution of a fringe image obtained by capturing a fringe pattern on a surface of an object using an optical digital camera comprising an imaging element arranged in a horizontal direction and a vertical direction, the method comprising: a step of obtaining one two-dimensional fringe image or a three-dimensional fringe image in which a plurality of two-dimensional fringe images are arranged in time series by capturing one image of the fringe pattern on the surface of the object or a plurality of images of the fringe pattern while shifting a temporal phase; a step of generating a plurality of phase-shifted moiré fringe images by performing at least a thinning-out process on intensity data of the one two-dimensional fringe image or the three-dimensional fringe image; a step of calculating a phase distribution of the moiré fringe images in the horizontal direction or the vertical direction by using fast Fourier transform or discrete Fourier transform on the phase-shifted moiré fringe images by a calculator; and step of calculating the phase distribution of the fringe pattern image on the object by adding a phase value of a thinning-out point in the thinning-out process to a value of each point in the phase distribution by the calculator.