Provided is a radiation phase-contrast imaging device capable of assuredly detecting a self-image and precisely imaging the internal structure of an object. According to the configuration of the present invention, the longitudinal direction of a detection surface of a flat panel detector is inclined with respect to the extending direction of an absorber in a phase grating. This causes variations in the position (phase) of a projected stripe pattern of a self-image at different positions on the detection surface. This is therefore expected to produce the same effects as those obtainable when a plurality of self-images are obtained by performing imaging a plurality of times in such a manner that the position of the projected self-images on the detection surface varies. This alone, however, results in a single self-image phase for a specific region of the object. Therefore, according to the present invention, it is configured such that imaging is performed while changing the relative position of the imaging system and the object.
