A switching device comprising: first wireless line terminating means for transmitting and receiving frames via a first wireless line; second wireless line terminating means for transmitting and receiving frames via a second wireless line; first line terminating means for exchanging frames with the first wireless line terminating means; second line terminating means for exchanging frames with the second wireless line terminating means; radio monitoring means for monitoring a state of the first and second wireless lines (51, 52), the radio monitoring means being arranged to instruct the first and second wireless line terminating means (21, 22) to exchange copy frames with the other wireless line terminating means (21, 22) and to abandon received frames, in accordance with a redundancy mode of the first and second wireless lines (51, 52); communication path control means for setting the first and second line terminating means (25, 26) to each be an active system or a standby system in accordance with a monitoring result obtained by the radio monitoring means as to the state of the wireless lines; and a switch core arranged to pass frames to be transmitted to the line terminating means (21, 22) operating as the active system, wherein the first and second wireless lines (51, 52) are subjected to a link aggregation so as to be treated as one virtual line, wherein in setting a first redundancy mode in which the first line terminating means operates as the active system and the second line terminating means operates as the standby system, the switch core is arranged to pass transmission frames to the first line terminating means, the radio monitoring means is arranged to instruct the first wireless line terminating means to pass copy frames of the transmission frames received from the first line terminating means to the second wireless line terminating means, the radio monitoring means is arranged to instruct the second wireless line terminating means to abandon frames received via the second wireless line, and the second wireless line terminating means is arranged to transmit the copy frames and abandon the received frames. first wireless line terminating means for transmitting and receiving frames via a first wireless line; second wireless line terminating means for transmitting and receiving frames via a second wireless line; first line terminating means for exchanging frames with the first wireless line terminating means; second line terminating means for exchanging frames with the second wireless line terminating means; radio monitoring means for monitoring a state of the first and second wireless lines (51, 52), the radio monitoring means being arranged to instruct the first and second wireless line terminating means (21, 22) to exchange copy frames with the other wireless line terminating means (21, 22) and to abandon received frames, in accordance with a redundancy mode of the first and second wireless lines (51, 52); communication path control means for setting the first and second line terminating means (25, 26) to each be an active system or a standby system in accordance with a monitoring result obtained by the radio monitoring means as to the state of the wireless lines; and a switch core arranged to pass frames to be transmitted to the line terminating means (21, 22) operating as the active system, wherein the first and second wireless lines (51, 52) are subjected to a link aggregation so as to be treated as one virtual line, wherein in setting a first redundancy mode in which the first line terminating means operates as the active system and the second line terminating means operates as the standby system, the switch core is arranged to pass transmission frames to the first line terminating means, the radio monitoring means is arranged to instruct the first wireless line terminating means to pass copy frames of the transmission frames received from the first line terminating means to the second wireless line terminating means, the radio monitoring means is arranged to instruct the second wireless line terminating means to abandon frames received via the second wireless line, and the second wireless line terminating means is arranged to transmit the copy frames and abandon the received frames.