Contact conditions of the testing probes for the testing of IC electrical conductivity were investigated. A method was proposed that could clarify the conditions for designing and selecting both the optimum probe geometry and the mechanical properties of pads suitable for effectively decreasing the contact electrical resistance. The elastic deformation of contact probes and the indenting plastic deformation of the pad surface were analyzed theoretically as a coupled problem. Deformations of the pad were mainly divided into two modes depending on the relative sliding velocity: a scratch type and an indentation divergence type. When the radius at the tip of a probe was larger than the thickness of the aluminum-deposited film, the deformation tends to be an indentation divergence. The expansion of the surface area generated at the contact region (surface expansion) and the amount of swelling by bulge deformation (bulge height) were found as important factors in the design of probes. The surface expansion, which indicates the probability of the appearance of a newly generated surface due to the breaking of the insulating oxidized film, affected strongly electrical conductivity. The bulge height, together with the frictional shear factor, influenced the apparent coefficient of friction between the probe and pad. These values can provide design criteria of contact probes for achieving stable electrical conduction.