An X-ray imaging apparatus acquiring a differential phase contrast image of a test object without using a light-shielding mask for X-ray. The apparatus includes an X-ray source, a splitting element configured to spatially divide an X-ray emitted from an X-ray source and a scintillator configured to emit light when a divided X-ray beam divided at the splitting element is incident on the scintillator. The apparatus also includes a light-transmission limiting unit configured to limit transmitting amount of the light emitted from the scintillator and a plurality of light detectors each configured to detect the amount of light that has transmitted through the light-transmission limiting unit. The light-transmission limiting unit is configured such that a light intensity detected at each of the light detectors changes in response to a change in an incident position of the X-ray beam.