An X-ray diffraction apparatus including an X-ray detector that is configured to detect diffracted X-rays diffracted from a sample when a surface of the sample is irradiated with X-rays, a counter arm which rotates around a rotation center axis set within the surface of the sample while the X-ray detector is installed on the counter arm, and a plate-like X-ray shielding member that is installed on the counter arm and rotated together with the X-ray detector.