To enable fluorescent X rays with a large intensity to enter a detector, prevent the background of other entire fluorescent X rays from increasing, and improve analysis performance by providing a filter for attenuating fluorescent X rays being generated from the main constituent element of a sample at a light path from the sample to the detector.

Primary X rays 2 of an X-ray source 3 are made incident on the surface of a silicon wafer 1 at a small angle, and totally reflected X rays 14 are allowed to escape in a direction where the X rays do not enter and energy-dispersion-type detector SSD 5. The X rays 2 are irradiated and X rays 4 being generated from a wafer 1 pass through a filter 6 of an SSD 5 and are detected by the SSD 5. The X rays 4 from the wafer 1 contain fluorescent X rays from such contaminant at iron to be analyzed and Ni and Si-Kα rays and increase the background of the entire fluorescent X rays, thus causing the detection lower limit of the contaminant to increase. The filter 6 transmits fluorescent X rays from a heavy element to be analyzed with a high efficiency and Si-Kα rays are transmitted only by approximately 10%, thus preventing the background from increasing.