In clad contacts of bonded dissimilar metals used in relays and switches, the bonding state affects the switching performance of those devices. Examining the bonding state and analyzing the relationship between the bonding state and the causes of malfunction, such as welding of the contact, leads to improvement in reliability of electromechanical devices. In this experiment we examined, with an ultrasonic microscope, the bonding state in riveted clad contacts which had been subjected to load-breaks of in-rush current, and were able to demonstrate the causal relation of the bonding state with malfunctions of the contacts. The use of the ultrasonic microscope made it possible to perform a hitherto difficult detailed analysis of the bonding state of clad contacts. It was also confirmed that this was an extremely effective method for studying the relationship with switching performance.