A planar waveguide-type optical switch comprising: a first base including a substrate, a plurality of planar waveguide pairs having different optical connection functions and arranged at predetermined pair spaces on the substrate, and a set of butting end faces, the respective end faces of waveguides constituting the plurality of waveguide pairs being exposed on the butting end faces at predetermined pitches; and second and third bases each having a joint end face butted to each corresponding butting end face of the first base, and provided with at least a set of optical fiber pairs optically connected to optical transmission routes and arranged at the same pitch as the waveguides, the respective end faces of optical fibers constituting the set of optical fiber pairs being exposed on the joint end faces. In this planar waveguide type optical switch, any of the first to third bases butt-connected to one another is moved parallel for the pair space of the planar waveguide pairs along the butting end face so that at least a set of optical fiber pairs of the second and third bases connected to a predetermined planar waveguide pair out of the plurality of planar waveguide pairs are optically connected to a desired planar waveguide pair, whereby the optical transmission routes are switched.