<p>The purpose of the present invention is to provide an optical composite sheet that can suitably propagate light. An optical composite sheet (1) is provided with: a first optical layer (10) and a second optical layer (20); and a low refractive index layer (30), which is laminated at least between the first optical layer (10) and the second optical layer (20), and has a refractive index lower than that of the first optical layer (10) and that of the second optical layer (20). The low refractive index layer (30) is characterized in including a large number of particles (50) having an average particle size of 5-300 nm, a binding resin (35) that binds together surface portions of the particles (50); and spaces (36) formed among the particles.</p>
