An X-ray stress measuring apparatus, for measuring stress on a sample, comprises: a pair of X-ray generating means (10, 11, 10′, 11′) for irradiating X-ray beams, determining an angle defined between the X-ray beams, mutually, at an arbitrary fixed angle, on a plane inclining by an angle desired with respect to a surface of the sample to be measured stress thereon; an X-ray sensor portion (29) for detecting plural numbers of Debye rings (C, C′), which are generated by incident X-ray beams from said pair of X-ray generating means; and a battery (410) for supplying necessary electricity to each of parts of the apparatus, wherein said X-ray sensor portion is made up with only one (1) piece of a 2-dimensional X-ray detector (20) or a 1-dimensional X-ray detector (20′), and is disposed in a position where the plural numbers of Debye rings generated by the incident X-ray beams from the at least one pair of X-ray generating means are adjacent to each other, or intersect with each other, thereby detecting the plural numbers of the Debye rings caused due to the X-ray and the X′-ray in common with.