The X-ray phase imaging apparatus includes a position switching mechanism for switching a relative position of one or more gratings between a retreated position which is an outside of a detection range on a detection surface of an image signal detector and a detection positon which is an inside of the detection range on the detection surface of the image signal detector and a focal diameter changing unit configured to change a focal diameter of the X-ray source in conjunction with switching of the relative position of the one or more gratings.
