To provide an X-ray measurement method and an X-ray measurement device that can totally grasp the crystal orientation property and mosaic property and the state of the interval between surfaces of crystal surfaces that are vertical to the surface of a sample to be measured.

An X-ray source 2, a goniometer device 3 with a traveling mechanism in three directions x, y, and z of at least a sample 10 to be measured and a rotary mechanism in one direction ω, an X-ray detector 4 for detecting X rays Xd being reflected by the sample 10, and an X-ray measuring device 1 with an X-ray rotary mechanism for changing directions θ and 2θ of the X-ray source 2 and the X-ray detector 3 for a measurement point M of the sample 10 to be measured are used, thus fixing a sample surface 10s so that it is vertical to the rotary mechanism of one direction ω and setting an incidence angle α of X rays to conditions for total reflection on the sample surface 10s.