A control network system that controls at least one wireless field device which is a control target by using control data of the at least one wireless field device, the control network system comprising: the at least one wireless field device that is adapted to transmit the control data and a network ID identifying a wireless network that the at least one wireless field device joins, through a wireless communication; at least one gateway apparatus (2, 3) that is adapted to relay the control data from the at least one wireless field device, the at least one gateway apparatus (2, 3) comprising a storage unit that stores an instrument commissioning state control table in which identification data identifying the at least one wireless field device, the network ID and a flag are stored, the flag being one of a nonsteady state flag showing that the at least one wireless field device is under commissioning and a steady state flag showing that the at least one wireless field device has finished commissioning; and a host system that is adapted to receive the control data and status information of the control data from the at least one wireless field device through the at least one gateway apparatus (2, 3) by transmitting access request information that requests the control data from the at least one wireless field device to the at least one gateway apparatus (2, 3), the host system comprising a control unit that is adapted to discontinue operation of controlling the at least one wireless field device when the flag is the nonsteady state flag, wherein the at least one gateway apparatus (2, 3) is adapted to receive access request information, which is output from the host system, and to determine whether or not the at least one wireless field device is under commissioning based on the flag, and wherein the at least one gateway apparatus (2, 3) further comprises: a status output unit that is adapted to turn the status information of the control data into the steady state or the nonsteady state based on the flag when receiving the access request information transmitted from the control unit; and a communication unit that is adapted to transmit both the control data and the status information to the control unit. the at least one wireless field device that is adapted to transmit the control data and a network ID identifying a wireless network that the at least one wireless field device joins, through a wireless communication; at least one gateway apparatus (2, 3) that is adapted to relay the control data from the at least one wireless field device, the at least one gateway apparatus (2, 3) comprising a storage unit that stores an instrument commissioning state control table in which identification data identifying the at least one wireless field device, the network ID and a flag are stored, the flag being one of a nonsteady state flag showing that the at least one wireless field device is under commissioning and a steady state flag showing that the at least one wireless field device has finished commissioning; and a host system that is adapted to receive the control data and status information of the control data from the at least one wireless field device through the at least one gateway apparatus (2, 3) by transmitting access request information that requests the control data from the at least one wireless field device to the at least one gateway apparatus (2, 3), the host system comprising a control unit that is adapted to discontinue operation of controlling the at least one wireless field device when the flag is the nonsteady state flag, wherein the at least one gateway apparatus (2, 3) is adapted to receive access request information, which is output from the host system, and to determine whether or not the at least one wireless field device is under commissioning based on the flag, and wherein the at least one gateway apparatus (2, 3) further comprises: a status output unit that is adapted to turn the status information of the control data into the steady state or the nonsteady state based on the flag when receiving the access request information transmitted from the control unit; and a communication unit that is adapted to transmit both the control data and the status information to the control unit. a status output unit that is adapted to turn the status information of the control data into the steady state or the nonsteady state based on the flag when receiving the access request information transmitted from the control unit; and a communication unit that is adapted to transmit both the control data and the status information to the control unit.