Regarding a X-ray photographing-tire apparatus and method, defining the reference plane as the plane perpendicular to the center axis of a tire mounted on a rotary device and passing through the X-ray source, and defining the reference line as the line headed from the center axis to the X-ray source within the reference plane, the X-ray source is oriented so that a predetermined azimuth range coincides with a predetermined angular range in which the reference line lies, within the reference plane, and a first line-sensor, being oriented parallel with the center axis, is placed within said predetermined azimuth range, in the radial outside of the tread portion TR of the tire, and the first line-sensor is placed at the position deviated from the plane defined by both reference line and the center axis, having two degrees of freedom of motion within the reference plane with orientation of the receiving surface kept constant.