An X-ray Talbot interferometer includes a source grating having a plurality of X-ray transmitting portions to transmit some X-rays from an X-ray source, a beam splitter grating configured to diffract the X-rays from the X-ray transmitting portions with a periodic structure to form interference patterns, an analyzer grating configured to block parts of the interference patterns, and a detector configured to detect X-rays from the analyzer grating. The X-ray transmitting portions of the source grating are arranged to form a periodic pattern in which spatial frequency components contained in a sideband resulting from modulation caused by the presence of an object are enhanced by superimposing the interference patterns corresponding to the respective X-ray transmitting portions. In the absence of any object, the positional relation between the periodic pattern and the grating pattern of the analyzer grating is substantially the same over the entire imaging field.