We have proposed a new nondestructive evaluation method for detecting the delamination between a Si chip and metallic bumps by applying a measurement of local surface deformation of the Si chip. Since the local deformation decreased when an underfill material is filled in the delaminated space, it is important to measure the surface deformation of a Si chip before and after filling the underfill. To confirm the local deformation at a Si chip surface, we made test flip chip structures. The predicted local displacement at the samples surface was detected by a white light interferometer.