Provided are an optical switch and an optical logic device. The optical switch includes a plate having a nanometer-sized thickness, a first slit formed in the plate, through which a first light passes, a second slit formed in the plate, separately from the first slit, through which a second light selectively passes, a plurality of first grooves formed on a first side of the first slit, between the first slit and the second slit, and a plurality of second grooves formed on a second side of the first slit, opposite the first side. The first light and the second light may have a phase difference and a focusing of the first light is turned on/off by controlling the second light.