A headlight module includes a light source, a light guide element, and a projection optical element. The light source emits light. The light guide element has a reflecting surface for reflecting light emitted from the light source and an emitting surface for emitting light reflected by the reflecting surface. The projection optical element projects light emitted from the emitting surface. In a direction of an optical axis of the projection optical element, an end portion on the emitting surface side of the reflecting surface includes a point located at a focal position of the projection optical element.