A mobile X-ray apparatus is provided with an X-ray source, an X-ray planar detector being arranged in such a manner as opposed to the X-ray source, a support (C-shaped arm) for linking and supporting the X-ray source and the X-ray planar detector, an angle input part for inputting a rotation angle at which the X-ray planar detector is rotated within a plane including the X-ray incidence plane, a rotation controller and a rotation mechanism for rotating the X-ray planar detector according to the rotation angle being inputted, an image generator for generating an image of the test subject based on the transmitted X-rays being detected, displays for displaying the image, and an image rotor for subjecting the image being displayed on the displays to a rotation process according to an amount of the rotation of the X-ray planar detector.