In the optical module, the number of optical components is decreased, so that the costs of the device are reduced, and so that optical loss is reduced. The present device comprises: an optical gate array in which a plurality of optical gate switches each employing a semiconductor optical amplifier element are arranged in parallel; a dividing/combining unit including: a plurality of first ports connected one to each of the plurality of optical gate switches forming the optical gate array; and a second port which performs dividing/combining of light with the first port; and an optical amplifier connected to the second port of the dividing/combining unit, wherein the optical gate array, the dividing/combing unit, and the optical amplifier are formed in an integrated manner.