A waveguide type optical switch that can reduce the number of intersections in a matrix optical switch having the configuration of connecting unit optical switches and optical combining devices or optical branching devices to have a connecting function from “multiple inputs to one output” to “one input to multiple outputs”. To reduce the number of intersections in an entire matrix optical switch, an optical combining device of M inputs and one output is divided into (M−1) pieces of unit optical combining elements each having two inputs and one output, which are arranged immediately after (N−1) pieces of respective output ports excluding one piece of the output port closer to the input in the matrix optical switch out of N pieces of the output ports in the optical switch of one input and N outputs.