An optical switching device the size and costs of which are reduced by decreasing the number of switching elements and which can flexibly accommodate the expansion of the number of ports. An optical demultiplexing section has 2n (n=1, 2, 3, . . . ) input ports and 2m (m>n) output ports and includes demultiplexing couplers for demultiplexing input optical packets. A switch fabric section includes optical gate elements for switching optical packets outputted from the optical demultiplexing section by switch drive control. An optical multiplexing section has 2m input ports and 2n output ports and includes multiplexing couplers for multiplexing the optical packets which pass through the optical gate elements. A scheduler exercises control over an entire optical packet switching process.