An X-ray apparatus includes: a mounting unit upon which an object to be measured is mounted; an X-ray generation unit that irradiates X-rays, from above the mounting unit or from below the mounting unit, to the object to be measured upon the mounting unit; an X-ray detector that acquires a transmission image of the object to be measured being irradiated by the X-rays; a first movement unit that moves at least one of the mounting unit, the X-ray generation unit, and the X-ray detector along a direction of irradiation of the X-rays; a position detection unit that detects a relative position of the mounting unit, the X-ray generation unit, and the X-ray detector; and a calculation unit that calculates a magnification of a transmission image of the object to be measured acquired by the X-ray detector, in a state in which deflection of the mounting unit has occurred while the object to be measured is mounted upon the mounting unit.