A substrate for an LED chip or a semiconductor laser chip, including a mounting surface on which an LED chip or a semiconductor laser chip is to be mounted, the mounting surface being one of two opposed main surfaces of the substrate: wherein the substrate is provided with a protection element for the LED chip or the semiconductor laser chip, the protection element comprising a voltage-dependent resistive layer embedded in the substrate, and comprising a first electrode and a second electrode each of which is in connection with the voltage-dependent resistive layer; wherein the LED chip or the semiconductor laser chip is to be mounted such that the LED chip or the semiconductor laser chip is positioned in an overlapping relation with the voltage-dependent resistive layer; wherein the protection element is a varistor element; wherein the first electrode has a divided form wherein the divided two pieces of the first electrode are positioned in contact with the substrate exposure surface of the voltage-dependent resistive layer, whereas the second electrode is positioned such that it is in contact with a substrate embedment surface of the voltage-dependent resistive layer or is accommodated in the interior of the voltage-dependent resistive layer in an opposed relation to the first electrode; wherein the varistor element is composed of serially-connected two varistor elements which share the second electrode provided on the substrate embedment surface of the voltage-dependent resistive layer or accommodated in the interior of the voltage-dependent resistive layer; and wherein a surface of the voltage-dependent resistive layer is exposed from the substrate such that the surface of the embedded voltage-dependent resistive layer is flush with the one or the other of the two opposed main surfaces of the substrate, wherein the size of the surface of the embedded voltage-dependent resistive layer is smaller than the size of the mounting surface on which the LED chip or the semiconductor chip is to be mounted. wherein the substrate is provided with a protection element for the LED chip or the semiconductor laser chip, the protection element comprising a voltage-dependent resistive layer embedded in the substrate, and comprising a first electrode and a second electrode each of which is in connection with the voltage-dependent resistive layer; wherein the LED chip or the semiconductor laser chip is to be mounted such that the LED chip or the semiconductor laser chip is positioned in an overlapping relation with the voltage-dependent resistive layer; wherein the protection element is a varistor element; wherein the first electrode has a divided form wherein the divided two pieces of the first electrode are positioned in contact with the substrate exposure surface of the voltage-dependent resistive layer, whereas the second electrode is positioned such that it is in contact with a substrate embedment surface of the voltage-dependent resistive layer or is accommodated in the interior of the voltage-dependent resistive layer in an opposed relation to the first electrode; wherein the varistor element is composed of serially-connected two varistor elements which share the second electrode provided on the substrate embedment surface of the voltage-dependent resistive layer or accommodated in the interior of the voltage-dependent resistive layer; and wherein a surface of the voltage-dependent resistive layer is exposed from the substrate such that the surface of the embedded voltage-dependent resistive layer is flush with the one or the other of the two opposed main surfaces of the substrate, wherein the size of the surface of the embedded voltage-dependent resistive layer is smaller than the size of the mounting surface on which the LED chip or the semiconductor chip is to be mounted.