A radiation imaging apparatus according to the present invention includes a radiation source, a reflective structure where at least three reflective substrates are arranged with an interval and radiations being incident into a plurality of passages whose both sides are put between the reflective substrate are reflected and parallelized by the reflective substrate at both sides of the passage to be emitted from the passage, a radiation detector, and an image construction unit that constructs an image of an object based on an intensity of the radiation which is emitted from each of the passages, transmits the object and is detected by the radiation detector. When one edge of the reflective structure is an inlet of the radiation and the other edge is an outlet of the radiation, a pitch of the reflective substrates at the outlet is larger than a pitch at the inlet.
