To shorten time required in the measurement of X-ray reflectivity or locking curve and to realize the measurement with an X-ray measuring apparatus of simple constitution.

An X-ray measuring apparatus is equipped with an X-ray source 1 emitting X-rays from a minute focus, a reflector 3 for reflecting X-rays emitted from the X-ray source 1 to converge reflected X-rays in one direction and a curved monochromator 2 for making X-rays emitted from the X-ray source monochromatic to be reflected the same and converging the reflected X-rays in a direction crossing the converging direction by the reflector almost at right angles. Herein, the reflector 3 and the curved monochrometer 2 are positioned so that the respective converging points of X-rays almost coincide with each other, and a sample S is arranged at the converging point of the monochromater 2 and X-rays reflected by the sample are detected by an X-ray detector 4.