To reduce the time from when imaging is performed until when a radiological image is generated by image processing.

The first and the second absorption-type gratings are disposed between an X-ray source and an X-ray image detector (FPD), and while the second absorption-type grating is relatively moved in a direction orthogonal to a grating line relative to the first absorption-type grating, an image data P_k is acquired at M scanning positions (k=0,1,...,M-1) that divide the grating period into M, and then stored in a memory 19. A communication means reads out a pixel data I_k(x,y) corresponding to the same pixel from each of the image data P_k stored in the memory 19, and transfers the data for each pixel sequentially. This transfer is performed in order of the pixels lined up in a scanning direction (x direction). A phase differential image generation part at the transfer destination calculates a phase differential value each time it receives a plurality of image data I_k(x,y) corresponding to the same pixel. A phase contrast image generation part performs integration processing each time one phase differential value is generated by the phase differential image generation part.