Abstract: A light bulb having a light diffusion structure is provided. The light bulb includes a light source, a cap, and a shell. The light source is secured to and electrically connected to the cap. The cap is adapted for connecting with a power supply for providing an electric current from the power supply to the light source for exciting the light source to emit a light. The shell is secured to the cap, and defines a space having an opening. The light source is received in the space of the shell from the opening, and the opening is sealed by the cap. A part of the shell is configured with a coarse surface, and the rest part of the shell is provided with an over coat layer.