A substrate for mounting a light-emitting element includes a substrate that is composed of a ceramic(s), a terminal for an element that is provided on a front surface of the substrate where a light-emitting element is mounted thereon, a terminal for a power source that is provided on the substrate where an external power source is connected thereto, and a wiring part that is provided inside the substrate and electrically connects the terminal for an element and the terminal for a power source. Furthermore, the wiring part includes a first conductor that extends in a surface direction of the substrate and a second conductor that extends substantially parallel to the first conductor on an opposite side of the front surface and is connected in parallel with the first conductor.