The present invention is directed to an optical switch, which appropriately optically connects input side optical fibers with output side optical fibers. The optical switch comprises an input side array unit, and an output side array unit. The array unit on the input side has an input side fiber array, a mirror array, and a direction adjustment mechanism. The input side fiber array has signal input optical fibers and at least one adjustment optical fiber. The mirror array has tilt variable mirrors to deflect signal light beams from the signal input optical fibers and at least one fixed mirror to reflect an adjustment light beam from the adjustment optical fiber. The direction adjustment mechanism adjusts a relative direction of the mirror array with respect to the input side fiber array. The array unit on the output side has an output side fiber array having signal output optical fibers.