The present invention relates to an object information obtaining apparatus that obtains information about a phase image of an object using information about an interference pattern produced by a shearing interferometer, the interference pattern being formed by an electromagnetic wave or electron beam passed through or reflected by the object. The apparatus includes a first obtaining unit configured to obtain information about a differential phase image of the object using the information about the interference pattern, a second obtaining unit configured to obtain information about contrast in each region of the interference pattern, a third obtaining unit configured to weight the information about the differential phase image using the information about the contrast to obtain information about a weighted differential phase image, and a fourth obtaining unit configured to integrate the information about the weighted differential phase image to obtain the information about the phase image of the object.