1. A radiation phase contrast imaging apparatus, comprising: a radiation emission unit having a plurality of electron sources, each for emitting an electron beam, and a target for emitting radiation through collision of the electron beam emitted from each electron source; a first grating in which grating structures for diffracting radiation emitted from the radiation emission unit are disposed periodically; a second grating in which grating structures for transmitting and shielding radiation diffracted by the first grating are disposed periodically; and a radiation image detector for detecting radiation transmitted through the second grating, wherein: the first and second gratings are disposed in an optical axis direction of the radiation so as to be able to substantially superimpose each image of the first grating formed based on radiation corresponding to each electron source on a surface of the second grating; and the radiation corresponding to each electron source is radiation that forms each phase image of the same subject on the radiation image detector by way of the first and second gratings.