To provide an X-ray detector capable of manufacturing the detector of wide dimension as an integrated body, and capable of reducing a use amount of scintillator powder containing heavy metal, without lowering greatly luminescent intensity of the detector, and an X-ray detecting device using the X-ray detector.

The scintillator powder and a translucent resin are kneaded and cured to prepare the X-ray detector. The X-ray detector is constituted to change a filled degree of the scintillator powder substantially continuously along a thickness direction, and the filled degree A in a photodetector side for converting light into electricity is higher than the filled degree B in an opposite face side, in the X-ray detector.