A multicast switching system with an input stage, a middle stage, and an output stage, comprising: a plurality of input switch elements (201, 202 and 203, and 401, 402, and 403) which are provided at the input stage, configured to receive streams from input sources, and transmit the received streams to the middle stage; a plurality of middle switch elements (211, 212 and 213, and 411, 412, 421 and 422) which are provided at the middle stage, configured to receive the streams transmitted from one or more of the plurality of input switch elements (201, 202 and 203, and 401, 402, and 403), and transmit the received streams to the output stage, the plurality of middle switch elements (211, 212 and 213, and 411, 412, 421 and 422) being grouped into a plurality of groups (410 and 420); and a plurality of output switch elements (221, 222 and 223, and 431, 432 and 433) which are provided at the output stage, configured to receive streams transmitted from one or more of the plurality of middle switch elements (211, 212 and 213, and 411, 412, 421 and 422), and output the received streams to output destinations, characterized in that wherein each of the plurality of input switch elements (201, 202 and 203, and 401, 402, and 403) is configured to perform a first routing process to the middle stage by allocating the plurality of groups (410 and 420) to each of the streams received from the input sources and transmitting the received streams to all of the plurality of allocated groups (410 and 420), and each of the plurality of output switch elements (221, 222 and 223, and 431, 432 and 433) is configured to perform a second routing process by receiving streams to be transmitted from the groups selected as a result of the first routing process, and outputting the received streams to the output destinations. a plurality of input switch elements (201, 202 and 203, and 401, 402, and 403) which are provided at the input stage, configured to receive streams from input sources, and transmit the received streams to the middle stage; a plurality of middle switch elements (211, 212 and 213, and 411, 412, 421 and 422) which are provided at the middle stage, configured to receive the streams transmitted from one or more of the plurality of input switch elements (201, 202 and 203, and 401, 402, and 403), and transmit the received streams to the output stage, the plurality of middle switch elements (211, 212 and 213, and 411, 412, 421 and 422) being grouped into a plurality of groups (410 and 420); and a plurality of output switch elements (221, 222 and 223, and 431, 432 and 433) which are provided at the output stage, configured to receive streams transmitted from one or more of the plurality of middle switch elements (211, 212 and 213, and 411, 412, 421 and 422), and output the received streams to output destinations, characterized in that wherein each of the plurality of input switch elements (201, 202 and 203, and 401, 402, and 403) is configured to perform a first routing process to the middle stage by allocating the plurality of groups (410 and 420) to each of the streams received from the input sources and transmitting the received streams to all of the plurality of allocated groups (410 and 420), and each of the plurality of output switch elements (221, 222 and 223, and 431, 432 and 433) is configured to perform a second routing process by receiving streams to be transmitted from the groups selected as a result of the first routing process, and outputting the received streams to the output destinations.