In this X-ray phase imaging apparatus, at least one of a plurality of gratings is composed of a plurality of grating portions arranged along a third direction perpendicular to a first direction along which a subject or an imaging system is moved by a moving mechanism and a second direction along which an X-ray source, a detection unit, and a plurality of grating portions are arranged. The plurality of grating portions are arranged such that adjacent grating portions overlap each other when viewed in the first direction.