A plane illumination apparatus has an optical device, an irradiation unit to irradiate the coherent light beams to the optical device. The irradiation unit makes the coherent light beams scan the surface of the optical device by changing propagation directions of the coherent light beams, the light guide plate comprises a light take-out portion specific zone to take out coherent light beams to outside while making coherent light beams propagate between a first end face on which coherent light beams from the optical device are incident and a second end face that is provided to face the first end face, and the specific zone is provided inside the light take-out portion or along the first end face, or along the second end face.