A radiation imaging apparatus comprising a plurality of sensor units each including a plurality of photoelectric converters, a substrate configured to support the plurality of sensor units, and a scintillator, wherein the scintillator comprises scintillator grains configured to convert radiation into light and a binder configured to make the scintillator grains adhere to each other, and the scintillator includes first portions provided between the plurality of sensor units and a second portion provided on the plurality of sensor units and the substrate.