Residual stress measurement by x-ray diffraction on small samples or small sampling area using a two-dimensional (2D) detector is discussed. A new approach in stress analysis using the two-dimensional diffraction data is based on a direct relationship between the stress tenser and the diffraction cone distortion. Since the whole or a part of the Debye ring is used for stress calculation, a 2D detector can measure stress with high sensitivity, high speed and high accuracy, even for micro-area. The laser-video sample alignment system can align the intended measurement spot accurately to the instrument center where the x-ray beam hits. The motorized XYZ stage can move the measurement spot precisely to the instrument center and map many sample spots automatically. The spotty, textured, or weak diffraction data can be treated by "virtual oscillation".