A light source module includes a light emitting diode and a wiring board. The light emitting diode (LED) chip group includes LED chips for red, green and blue colors. A plurality of the LED chip groups are mounted on the wiring board. A surface on one side of the wiring board is a device forming surface including the plurality of the LED chip groups, an external connecting terminal for leading out electrodes, and a wiring pattern for electrical connection between the LED chip groups and the external connecting terminal. A surface on the other side of the wiring board is a heat radiating surface which is thermally connected to the device forming surface and operative to radiate heat generated at the device forming surface to the exterior.