A relaying device (2, 2A, 2B) comprising: an uplink interface which is configured to continuously receive an audio signal in communication; a wireless apparatus interface to which a half-duplex type of repeater (3, 3A, 3B) acting as a wireless relaying apparatus is connected, the repeater (3, 3A, 3B) being configured to reserve a wireless communication channel to send and receive the audio signal and configured to send and receive the audio signal between the repeater (3, 3A, 3B) and a wireless apparatus; a voice buffer which is configured to buffer the audio signal; and a control unit which is configured to receive the continuously received audio signal, transfer the continuously received audio signal to the repeater (3, 3A, 3B) via the wireless apparatus interface, and perform a VOX processing of detecting whether a level of the audio signal is equal to or higher than a preset threshold or not, wherein only a zone of a voice sound is transferred to the repeater (3, 3A, 3B) among the continuously received audio signal, wherein when the level of the audio signal is detected as being equal to or higher than the preset threshold in the VOX processing, the control unit is configured to determine the audio signal as the voice sound and start buffering, in the voice buffer, an audio signal of the voice sound to be transferred to the repeater (3, 3A, 3B), and when the level of the audio signal is detected as being lower than the preset threshold in the VOX processing, the control unit is configured to stop buffering the audio signal, when a zone of the voice sound is started, the control unit is configured to request the repeater (3, 3A, 3B) to reserve a wireless communication channel, and after receiving, from the repeater (3, 3A, 3B), a reply indicating that the wireless communication channel has been reserved, the control unit is configured to read the audio signal buffered in the voice buffer and transfer this audio signal to the repeater (3, 3A, 3B) to set the repeater (3, 3A, 3B) to turn on a transmission state. an uplink interface which is configured to continuously receive an audio signal in communication; a wireless apparatus interface to which a half-duplex type of repeater (3, 3A, 3B) acting as a wireless relaying apparatus is connected, the repeater (3, 3A, 3B) being configured to reserve a wireless communication channel to send and receive the audio signal and configured to send and receive the audio signal between the repeater (3, 3A, 3B) and a wireless apparatus; a voice buffer which is configured to buffer the audio signal; and a control unit which is configured to receive the continuously received audio signal, transfer the continuously received audio signal to the repeater (3, 3A, 3B) via the wireless apparatus interface, and perform a VOX processing of detecting whether a level of the audio signal is equal to or higher than a preset threshold or not, wherein only a zone of a voice sound is transferred to the repeater (3, 3A, 3B) among the continuously received audio signal, wherein when the level of the audio signal is detected as being equal to or higher than the preset threshold in the VOX processing, the control unit is configured to determine the audio signal as the voice sound and start buffering, in the voice buffer, an audio signal of the voice sound to be transferred to the repeater (3, 3A, 3B), and when the level of the audio signal is detected as being lower than the preset threshold in the VOX processing, the control unit is configured to stop buffering the audio signal, when a zone of the voice sound is started, the control unit is configured to request the repeater (3, 3A, 3B) to reserve a wireless communication channel, and after receiving, from the repeater (3, 3A, 3B), a reply indicating that the wireless communication channel has been reserved, the control unit is configured to read the audio signal buffered in the voice buffer and transfer this audio signal to the repeater (3, 3A, 3B) to set the repeater (3, 3A, 3B) to turn on a transmission state.