An X-ray diffractometer for obtaining X-ray diffraction angles of diffracted X-rays by detecting with an X-ray detector diffracted X-rays diffracted at a sample when X-rays are emitted at the sample at each angle of the angles about a center point of goniometer circles, the X-ray diffractometer having a pinhole member provided with a pinhole, the pinhole allowing X-rays diffracted from the sample to pass so that the diffracted X-rays pass through the center point of the goniometer circle, and other diffracted X-rays are shielded by the pinhole member.