1. An X-ray imaging apparatus comprising: a splitting element that spatially splits X-rays generated by an X-ray generating unit; a detecting unit that detects each intensity of the split X-rays split by said splitting element and transmitted through a detection object; a transport unit that moves the X-ray generating unit, said splitting element, the detection object or said detecting unit; a transport control unit that controls a scanning time of the X-rays irradiated onto the detection object by means of said transport unit; an exposure control unit that synchronizes the scanning time of the X-rays and an image acquisition time of said detecting unit; and a computing unit that computes a differential phase contrast image or a phase contrast image of the detection object from the information acquired by said detecting unit.