A new X-ray stress measuring technique – dual-axis inclining method – has been developed to measure stress on a flat surface at confined area like a side-wall of V-groove non-destructively. This technique allows one to measure two mutually orthogonal stress components of the side-wall – the normal stress in the groove-height direction σ_T and that in the groove-line direction σ_L – without eliminating a facing side-wall. This technique is characterized by the combination of the iso-inclination scanning (ψ angle) and the side-inclination scanning (Ω angle). The iso-inclination scanning in the plane including the groove-line leaving the side-wall inclined from the reference axis of goniometer's rotation, i.e. the ψ rotation under Ω ≠ 0deg, gives an apparent stress in the groove-line direction. Measuring the relation between the apparent stress and sin²Ω for available range on Ω in which the X-ray path is not prevented by the facing side-wall, one can obtain σ_L from the y-intercept by extrapolating the regression line of the relation to sin²Ω = 0 and σ_T from the gradient of the regression line. The validity of this technique was verified by applying this technique and the conventional method to a flat specimen respectively, and comparing the values measured.