In a wireless communication system, a sender apparatus sends a data block, for each of a plurality of stream data, with data block identification information, which does not conflict between stream data, annexed, and a reception apparatus performs a re-sending synthesis process for a data block received already and a re-sending data block to which the same data block identification information is individually annexed based on the data block identification information annexed to the received data block. Consequently, also in a case wherein the number of transmission streams between the sender apparatus and the reception apparatus is varied (reduced), the matching property of the data block which is a re-sending synthesis target can be maintained and communication can be continued normally.