Abstract: A method of manufacturing an optical isolator which has a rotator capable of rotating a plane of polarization by the Faraday effect, and a polarizer of multilayer structure formed of alternately superposed transparent dielectric films and films having a complex dielectric constant, includes the steps of: forming the rotator as a plate having a large area and the polarizer as an array having a large area; forming an optical isolator array by attaching the polarizer array at least to one surface of the rotator plate in such a manner that the layers of the polarizer array extend perpendicularly to the surface of the rotator plate; and cutting the optical isolator array into a plurality of optical isolator chips.