A nerve conduction test checks whether the function of a nerve to conduct action potentials is normal or not by measuring compound action potential on the skin. In some neuropathies, a decrease in the thickness of the myelin sheath is observed. This is considered to be a cause of any delay or decay of the conduction of compound action potentials. However degenerated nerves include those with missing nerve fibers, which also decreases the velocity and amplitude of the potential. To investigate the effect of myelin sheath exfoliation, the compound action current was defined as modeling the source of compound action potentials, which are constructed as a complex of axonal currents of each nerve fiber inside a nerve. As a result, the thickness of the nerve fiber contributed to slowing the velocity of the current wave; however, the amplitude of the wave did not always decrease.