An apparatus for radiographing an object using radiation from a movable radiation source, includes a detection unit which detects a radiation image of an object, a supporting unit which supports the object, and a control unit which controls a movement of at least one of the detection unit and the supporting unit, based on information of a position of the radiation source and a part to be radiographed of the object, such that a projection image of the part to be radiographed can be detected by the detection unit.