An optical element includes at least with a Faraday rotator of which both light-transmission surfaces are bonded through a bonding layer to light-transmission surfaces of polarization glasses which are orientationally dispersed with anisotropically-shaped particles at their surfaces. Each of the polarization glasses includes the orientationally dispersed anisotropically-shaped particles only at one surface opposite to the bonding surface. A relation t≧30 μm is satisfied, wherein t denotes a distance between one of the bonding surfaces of the Faraday rotator and that surface of the polarization glass on the one of the bonding surfaces of the Faraday rotator which is disposed with the particles. As a result, high isolation (25 dB or higher) can be maintained, even if a polarization glass which includes a thin layer with orientationally dispersed anisotropically-shaped particles is used.