PURPOSE: To obtain an optical switch which is easy to manufacture without limitation in material system by constituting a super lattice thin film forming a switching region of the same material of n type and p type.

CONSTITUTION: Stripe-shaped electrodes 5-1 for impressing an electric field are provided to a cross part 4-1 forming the switching region such as optical waveguides 2-1 and 3-1 having the refractive index higher than the refractive index of the circumference provided to a single crystal substrate 1 of a III-V compd. semiconductor. The refractive index of the part 4-1 changes according to the electric current to be impressed to the electrodes 5-1, by which the reflection and diffraction of the propagated light are controlled and the propagated light is switched. The part 4-1 is constituted of the ni-pi type super lattice thin film laminated alternately with the III-V compd. semiconductor which is the same material of the n type and p type. Since said film is not such a hetero type super lattice thin film as InP-InGaAsP, there is no limitation for the material system and the optical switch which can be easily manufactured is obtd.