There is provided an optical receiver. The optical receiver includes a board to be coupled with an optical transmission line array, an optical diode array disposed on the board, and the optical diode array including a plurality of photo diodes each of which receives light from a corresponding optical transmission line in the optical transmission array. Further bias suppliers, conversion circuits, and capacitors are provided on the board or a real side of the board. Each of the photo diodes includes a first electrode and second electrodes, the first electrode receives a bias voltage supplied by a bias supplier, a current signal flowing through the second electrode is converted by a conversion circuit into a voltage signal, and one end of a capacitor is coupled to the first electrode and the other is grounded.