The present invention provides a technology capable of conducting an accurate non-destructive inspection of a moving subject. A radiation source unit 1 irradiates radioactive rays toward gratings G0 to G2. Each grating G0 to G2 includes a plurality of grating members. A radioactive ray detector unit 3 detects the radioactive rays diffracted by the plurality of grating members. The plurality of grating members are arranged with a predetermined phase difference such that moire pattern images respectively formed by the radioactive rays transmitted through first to third partial areas 71 to 73 have a phase difference between the moire pattern images.