A relay station for a wireless relay system comprising two terminal stations (10A, 10B) that perform random access and a plurality of relay stations (30A, 30B, 30C) that relay communication between the two terminal stations, the relay station comprising: a slot synchronization unit adapted to synchronize slot timing of a time slot indicating a unit time; a time synchronization unit adapted to perform time synchronization for synchronization of the slot timing; and a transmission unit adapted to transmit a transmission packet to an adjacent terminal station or an adjacent relay station via a wireless line in synchronization with the slot timing, wherein in the wireless relay system, the relay stations are divided into a plurality of groups, and a relay station and an adjacent relay station are assigned to two different groups among the plurality of groups, wherein a transmission right is allocated for at least one time slot to each of the groups, wherein transmission by random access being permitted only in the time slot to which the transmission right is allocated, wherein said transmission unit is adapted to transmit the transmission packet to the wireless line only in the time slot in which the transmission right is allocated to the group to which the relay station belongs, wherein transmission rights for transmissions in different time slots are allocated to the groups, wherein radio waves of each of the terminal stations interfere with radio waves of a relay station that is adjacent to each of the terminal stations but does not interfere with radio waves of a relay station that is adjacent to a relay station that is adjacent to each of the terminal stations, radio waves of each of the relay stations interfere with radio waves of a relay station or a terminal station that is adjacent to each of the relay stations but does not interfere with radio waves of a relay station or a terminal station that is adjacent to a relay station that is adjacent to each of the relay stations, each of the terminal stations and a relay station that is adjacent to a relay station that is adjacent to each of the terminal stations are able to perform simultaneous transmission using the same frequency channel, and each of the relay stations and a relay station or a terminal station that is adjacent to a relay station that is adjacent to each of the relay stations are able to perform simultaneous transmission using the same frequency channel, and wherein the two terminal stations perform random access on every time slot. a slot synchronization unit adapted to synchronize slot timing of a time slot indicating a unit time; a time synchronization unit adapted to perform time synchronization for synchronization of the slot timing; and a transmission unit adapted to transmit a transmission packet to an adjacent terminal station or an adjacent relay station via a wireless line in synchronization with the slot timing, wherein in the wireless relay system, the relay stations are divided into a plurality of groups, and a relay station and an adjacent relay station are assigned to two different groups among the plurality of groups, wherein a transmission right is allocated for at least one time slot to each of the groups, wherein transmission by random access being permitted only in the time slot to which the transmission right is allocated, wherein said transmission unit is adapted to transmit the transmission packet to the wireless line only in the time slot in which the transmission right is allocated to the group to which the relay station belongs, wherein transmission rights for transmissions in different time slots are allocated to the groups, wherein radio waves of each of the terminal stations interfere with radio waves of a relay station that is adjacent to each of the terminal stations but does not interfere with radio waves of a relay station that is adjacent to a relay station that is adjacent to each of the terminal stations, radio waves of each of the relay stations interfere with radio waves of a relay station or a terminal station that is adjacent to each of the relay stations but does not interfere with radio waves of a relay station or a terminal station that is adjacent to a relay station that is adjacent to each of the relay stations, each of the terminal stations and a relay station that is adjacent to a relay station that is adjacent to each of the terminal stations are able to perform simultaneous transmission using the same frequency channel, and each of the relay stations and a relay station or a terminal station that is adjacent to a relay station that is adjacent to each of the relay stations are able to perform simultaneous transmission using the same frequency channel, and wherein the two terminal stations perform random access on every time slot.