The invention provides an LED module with an optical diffusion layer formed to serve as a mirror around LEDs for attaining irregular reflection of light by few LEDs so as to disperse the light from an angled layer for dispersing the light angle and to secondarily dispersing light from another irregular reflection layer, thereby uniformly distributing the light on a light emitting surface when using the LED as an illumination light source member. The LED module includes the optical diffusion layer formed to include a heat radiation diffusion plate having irregularly reflecting diffusion layersformed on its both sides and a U-shaped insertion port formed in its central upper end; a light emitting section having a PCB substrate coupled into the insertion port by a press-in method, a waterproof resin layer formed on an upper surface of the PCB substrate 21, input/output connectors for power supply formed on upper surface both ends of the waterproof resin layer and the LEDs3 longitudinally disposed between the input/output connectors; and a double-sided tape longitudinally attached to the bottom of the heat radiation diffusion plate to fix the heat radiation diffusion plate to a framewith a lid.