There are provided a light-source circuit unit, an illumination device, and a display device which are capable of extracting light emitted from the back surface of a light-emitting element chip to the front surface, suppressing a reduction in reflectance, and reducing cost, with a simple configuration. The light-source circuit unit includes a circuit substrate that has a light-reflective wiring pattern on a surface thereof and includes a chip mounting layer as a part of the wiring pattern, and one or more light-emitting element chips that are directly placed on the chip mounting layer, and are driven by a current flowing through the wiring pattern.