A data relay system comprising: a master station apparatus that functions as a master station in a higher-level TDMA system; a plurality of slave station apparatuses (21 to 23, 31 to 33, 41 to 43, 51 to 53, 61 to 63) that function as slave stations in a plurality of lower-level TDMA systems (102, 103, 104, 105, 106); and a plurality of repeating apparatuses (20,30,40, 50, 60) that relay communication between the master station apparatus and the slave station apparatuses (21 to 23, 31 to 33, 41 to 43, 51 to 53, 61 to 63), the repeating apparatuses functioning as slave stations in the higher-level TDMA system and functioning as respective master stations in the plurality of lower-level TDMA systems (102, 103, 104, 105, 106), characterized in that N is an integer equal to or larger than 2, each of N operating periods includes M frames, M is a total number of the higher-level TDMA system and the plurality of lower-level TDMA systems, at least one of the N operating periods is a statically allocated time, and a dynamically allocated time includes the N operating periods other than the statically allocated time, wherein the master station apparatus is adapted to allocate frames of the statically allocated time to each of the higher-level TDMA system and the plurality of lower-level TDMA systems (102, 103, 104, 105, 106), allocate frames of the dynamically allocated time to the higher-level TDMA system and the plurality of lower-level TDMA systems (102, 103, 104, 105, 106) with distribution depending on communication states between the master station apparatus and the plurality of repeating apparatuses (20, 30, 40, 50, 60) in the higher-level TDMA system during the statically allocated time, and transmit an allocation result indicating at least the allocated frames in the dynamically allocated time to the repeating apparatuses (20, 30, 40, 50, 60), and each of the repeating apparatuses (20, 30, 40, 50, 60) is adapted to extract, based on the allocation result received from the master station apparatus, the allocated frame allocated to the own apparatus and operates as the master station in the extracted frame. a master station apparatus that functions as a master station in a higher-level TDMA system; a plurality of slave station apparatuses (21 to 23, 31 to 33, 41 to 43, 51 to 53, 61 to 63) that function as slave stations in a plurality of lower-level TDMA systems (102, 103, 104, 105, 106); and a plurality of repeating apparatuses (20,30,40, 50, 60) that relay communication between the master station apparatus and the slave station apparatuses (21 to 23, 31 to 33, 41 to 43, 51 to 53, 61 to 63), the repeating apparatuses functioning as slave stations in the higher-level TDMA system and functioning as respective master stations in the plurality of lower-level TDMA systems (102, 103, 104, 105, 106), characterized in that N is an integer equal to or larger than 2, each of N operating periods includes M frames, M is a total number of the higher-level TDMA system and the plurality of lower-level TDMA systems, at least one of the N operating periods is a statically allocated time, and a dynamically allocated time includes the N operating periods other than the statically allocated time, wherein the master station apparatus is adapted to allocate frames of the statically allocated time to each of the higher-level TDMA system and the plurality of lower-level TDMA systems (102, 103, 104, 105, 106), allocate frames of the statically allocated time to each of the higher-level TDMA system and the plurality of lower-level TDMA systems (102, 103, 104, 105, 106), allocate frames of the dynamically allocated time to the higher-level TDMA system and the plurality of lower-level TDMA systems (102, 103, 104, 105, 106) with distribution depending on communication states between the master station apparatus and the plurality of repeating apparatuses (20, 30, 40, 50, 60) in the higher-level TDMA system during the statically allocated time, and transmit an allocation result indicating at least the allocated frames in the dynamically allocated time to the repeating apparatuses (20, 30, 40, 50, 60), and transmit an allocation result indicating at least the allocated frames in the dynamically allocated time to the repeating apparatuses (20, 30, 40, 50, 60), and each of the repeating apparatuses (20, 30, 40, 50, 60) is adapted to extract, based on the allocation result received from the master station apparatus, the allocated frame allocated to the own apparatus and operates as the master station in the extracted frame.