An X-ray diagnostic apparatus includes an X-ray tube for irradiating a subject with X-rays, a rectangular planar type X-ray detector formed by arraying a plurality of solid-state detection elements, a supporting mechanism for supporting the X-ray tube and the planar type X-ray detector in arbitrary postures with respect to the subject, and a suspending mechanism for suspending the planar type X-ray detector from the supporting mechanism. The suspending mechanism has a rotating mechanism for rotating the planar type X-ray detector through an arbitrary angle about a central path of the X-rays. When necessary, the planar type X-ray detector is rotated about the central path of the X-rays so as to be very close to the subject. When necessary, the planar type X-ray detector is rotated, so that the longitudinal direction of the subject on the image and the vertical direction of the screen can coincide with each other.