Power source unit and illumination device

A power source unit, comprising:

• a substrate including a plurality of light-emitting elements mounted thereon;
• and
• a reflective body including:
• a plurality of incident openings each corresponding to one of said plurality of light-emitting elements;
• an output opening to which light that has passed through each incident opening is output;
• and
• a plurality of reflective surfaces that expand from each incident opening toward each output opening,
• reflective surfaces included in said plurality of reflective surfaces and positioned on an outermost side are provided to be adjacent to one another, and the reflective body satisfying the following relationship:
• x≦45−θ1/2,
• where an angle formed by a reflective surface formed on an outer side and a surface in a direction perpendicular to a substrate surface is x, and an angle formed by a light beam emitted from the light-emitting elements and the surface substrate is θ1.