Abstract: A patient positioning device in a medical panorama X-ray photographing apparatus in which after data of the relative position of the subject to the X-ray photographing apparatus supplied from a sensor is compared with data of the relative position of a tomographic zone to the X-ray photographing apparatus thus to produce comparison data which is in turn transmitted to a drive circuit, a tomograph forming assembly and/or the subject is moved from coinciding with each other. The device further includes a comparing arithmetic circuit in which the detected position data of the subject and position data of the tomographic zone are arithmetically compared in order to improve operatability and positioning accuracy. The device furthermore includes a sensor which is adjustable for angular and vertical setting with the use of sensing position changing means in order to improve adaptability to individualities of the subject.