A radiation imaging apparatus includes: a housing configured to be hollow and extend along a first axial direction; a radiation emitter configured to be disposed in the housing and emit radiation along an optical axial direction perpendicular to the first axial direction; protruding units configured to extend along a second axial direction perpendicular to the first axial direction and the optical axial direction, and disposed to be fixed to both sides of the radiation emitter; and pressing units including an inclined unit disposed to contact at least one of the protruding units, so that the inclined unit and the at least one of the protruding units support each other.