Disclosed is a diffraction microscopy capable of reducing influence of an increase in the incident angle range of a beam. Specifically disclosed is a diffraction microscopy in which a beam is incident on a sample, in which the intensity of a diffraction pattern from the sample is measured, and in which an image of an object is rebuilt using Fourier interactive phase retrieval on the basis of the measured intensity of the diffraction pattern. In this method, Fourier interactive phase retrieval is performed using deconvolution on the diffraction pattern subjected to convolution by the increase in the incident angle range of the beam.