The detection surface of each of a plurality of detection elements is arranged on an arc along a diffractometer circle (reference circle). This allows each detection element to detect X-rays diffracted by a specimen at the focal position. Because this prevents errors in the X-ray intensity detected by each detection element, more accurate diffraction information can be obtained. As a result, a more accurate analysis can be performed in less time by detecting X-rays diffracted by the specimen using a plurality of detection elements.