The authors investigate the insulator-layer-thickness-dependent temperature increment in the nanowire for the current-induced domain wall motion. Practically, a finite thickness insulator layer must be placed between the semi-infinite substrate and the metallic nanowire for an electric insulation. Since a good electric insulator is also a thermal insulator, the temperature increment of the nanowire depends on the insulator layer's thickness. An approximated analytic expression of the insulator thickness dependent temperature increment is obtained by employing the Fourier-transformed Green's function method, and it is confirmed by the full numerical finite element method. The authors find that the control parameter of the temperature increment is the ratio between the insulator layer's thickness and the nanowire's width.