A light-emitting element module includes a temperature adjustment element, a light-emitting element arranged on a temperature adjustment surface of the temperature adjustment element, a metal layer arranged on the temperature adjustment surface, a relay member arranged on the temperature adjustment surface through the metal layer, a wiring layer arranged on a surface of the relay member at an opposite side to the temperature adjustment surface, a wiring to electrically connect the light-emitting element and the wiring layer, and a wiring to electrically connect a connection electrode and the wiring layer. The wiring layer has an area smaller than an area of a region where the metal layer overlaps the relay member in a plan view.