An X-ray diffraction apparatus comprising: a sample stage configured to hold a sample (S); 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 (S) when a surface of the sample (S) 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 (S) 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 (S) increases while a position within a plane flush with the surface of the sample (S) 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 (S) 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 (S) 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 (S) 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 (S); 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 (S) when a surface of the sample (S) 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 (S) 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 (S) increases while a position within a plane flush with the surface of the sample (S) 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 (S) 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 (S) 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 (S) 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 . <EOS>