An optical device includes: a first electrode; a second electrode; a refractive index adjustment layer that has a refractive index changing in response to an electric field and is changeable between a transparent state and a state in which the refractive index adjustment layer distributes incident light; and a textured layer including a plurality of protrusions protruding toward the second electrode. The refractive index adjustment layer is provided between the first electrode and the second electrode. The textured layer is provided between the first electrode and the refractive index adjustment layer. The plurality of protrusions is in the form of stripes. The protrusion has a substantially trapezoidal cross-section. A trapezoid which is a cross-sectional shape of the protrusion has a base angle θ at both ends of the lower base ranging from 70 degrees to 85 degrees.