A display device includes an optical waveguide layer, a variable refractive index layer, and an optical layer. The refractive index of the variable refractive index layer changes in response to application of a drive voltage. The optical layer reflects or absorbs light. The variable refractive index layer reflects the light to be guided through the optical waveguide layer 11 toward the inside of the optical waveguide layer depending on the refractive index of the variable refractive index layer to allow the optical waveguide layer to guide the reflected light. The variable refractive index layer introduces the light to be guided through the optical waveguide layer into the variable refractive index layer depending on the refractive index of the variable refractive index layer and emits the introduced light out of the variable refractive index layer. The optical layer reflects or absorbs the light emitted from the variable refractive index layer.