There is provided an optical matrix switch which comprises a branch-selective network and has, in its center stage, a transmittance-variable optical switch (a gate) with one input and one output. Varying the transmittance of the gate can reduce crosstalk between channels, and, if necessary, can control the power of optical channels. An optical ADM is also provided. In this optical ADM, a first level controller is provided between first and second optical switches for drop and add and controls the level of transmitted light, the level of an optical signal dropped is controlled in a second level controller, and the level of an optical signal added is controlled in a third level controller. The individual members are provided in an integral form on a single substrate. This can realize a reduction in size and a reduction in weight of an optical ADM. Further, this facilitates the control of a variation in loss in each path and the control of the level of optical signals in a terminal for drop and a terminal for add.