To solve the problem of a conventional optical isolator that polarizers need to be individually formed and optical adjustments of Faraday rotator and 1st and 2nd polarizers are inevitable.

On one surface of a substrate having Faraday rotator function, a 1st anti-reflection layer, a 1st polarizer layer, and a 2nd anti-reflection layer are laminated. On the other surface, a 1st anti-reflection layer, a 2nd polarizer layer, and a 2nd anti-reflection layer are laminated. The planes of polarization of the 1st polarizer layer and 2nd polarizer layer are tilted by the angle of rotation of the substrate having the Faraday rotator function.