An X-ray diffraction apparatus comprising: a sample stage configured to hold a sample; an X-ray source configured to emit X-rays; an X-ray detector that is configured to detect diffracted X-rays diffracted from the sample when a surface of the sample is irradiated with X-rays emitted from the X-ray source; and a counter arm that is configured to rotate around a rotation center axis set within the surface of the sample while the X-ray detector is installed on the counter arm, the counter arm is configured to rotationally scan the X-ray detector to a high angle side where an inclination angle of the X-ray detector with respect to the surface of the sample increases while a position within a plane flush with the surface of the sample is set as an origin of scanning on a low angle side, wherein the X-ray diffraction apparatus further comprises a plate-like X-ray shielding member that is installed on the counter arm and rotated together with the X-ray detector, the plate-like X-ray shielding member is arranged on a high angle side with respect to diffracted X-rays that are diffracted from the sample and incident to the X-ray detector, a distal end of the plate-like X-ray shielding member facing the sample is configured to approach the sample without interfering with the sample stage, and a surface portion of the plate-like X-ray shielding member is inclined with respect to a straight line connecting the distal end of the plate-like X-ray shielding member and the center of an X-ray irradiation region on the surface of the sample so as to shield scattered X-rays which may be incident from a high angle side of diffracted X-rays to the X-ray detector. a sample stage configured to hold a sample; an X-ray source configured to emit X-rays; an X-ray detector that is configured to detect diffracted X-rays diffracted from the sample when a surface of the sample is irradiated with X-rays emitted from the X-ray source; and a counter arm that is configured to rotate around a rotation center axis set within the surface of the sample while the X-ray detector is installed on the counter arm, the counter arm is configured to rotationally scan the X-ray detector to a high angle side where an inclination angle of the X-ray detector with respect to the surface of the sample increases while a position within a plane flush with the surface of the sample is set as an origin of scanning on a low angle side, wherein the X-ray diffraction apparatus further comprises a plate-like X-ray shielding member that is installed on the counter arm and rotated together with the X-ray detector, the plate-like X-ray shielding member is arranged on a high angle side with respect to diffracted X-rays that are diffracted from the sample and incident to the X-ray detector, a distal end of the plate-like X-ray shielding member facing the sample is configured to approach the sample without interfering with the sample stage, and a surface portion of the plate-like X-ray shielding member is inclined with respect to a straight line connecting the distal end of the plate-like X-ray shielding member and the center of an X-ray irradiation region on the surface of the sample so as to shield scattered X-rays which may be incident from a high angle side of diffracted X-rays to the X-ray detector.