An optical element mounting package includes a recess, a mounting portion for an optical element, and a reflector. The mounting portion is at a bottom surface of the recess. The reflector is, in the recess, positioned forward in an emission direction of light of the optical element. A first portion is a portion of an inner side surface of the recess, and is positioned in an opposite direction to the emission direction. The first portion has an inclined surface toward the bottom surface of the recess.