X-ray diffraction is an essential technology for material development, such as evaluating the degree of orientation and residual stress in metals and ceramics, in addition to qualitative and quantitative analysis of materials. Evaluating the crystalline state of micro-areas using X-rays has attracted significant attention with the increase in the miniaturization of devices. Micro-area X-ray diffraction can be performed by a laboratory system by equipping the diffractometer with focusing optics that produce a micro-sized beam while minimizing loss in beam intensity, and a highly sensitive detector. We herein illustrate an example of evaluating the residual stress (RS) in a very small area using a multilayer capacitor approximately 1 mm long.