The present invention provides an X-ray analysing apparatus having high sensitivity and high position resolving power in which an X-ray fluorescent screen (48) including Gd₂O₂S : Tb as a material and having a surface density ranging from 5 mg/cm² to 30 mg/cm² is used, and an image intensifier (50) and a charge coupled device (CCD) (52) are combined to construct an X-ray diffraction two-dimensional detector; and also an image intensifier tube and the CCD are combined with a tapered fibre plate (49), and an alignment section of the mirror mount tube and a vacuum flexible tube are separated by an X-ray window into the atmosphere and the vacuum.