A wireless device comprising: a wireless module configured to wirelessly transmit a signal which has been received from a field device, and wirelessly receive a signal which is to be transmitted to the field device; and an interface module which is disposed between the wireless module and the field device, wherein one of the wireless module and the interface module is configured to generate a first message having a predetermined format, the first message includes data and type information, the data is to be transmitted to other one of the wireless module and the interface module, the type information represents a type of the data, and the one of the wireless module and the interface module is configured to transmit the first message to the other one of the wireless module and the interface module, wherein the other one of the wireless module and the interface module is configured to generate a second message in accordance with the type information included in the first message, the second message includes data and type information, the data is to be replied to the one of the wireless module and the interface module, the type information represents a type of the data, and the other one of the wireless module and the interface module is configured to reply the second message to the one of the wireless module and the interface module, wherein in a case that the type information included in the first message represents notifications or instructions, the other one of the wireless module and the interface module is configured to perform processing in accordance with the notifications or the instructions, and do not reply the second massage to the one of the wireless module and the interface module; and wherein in a case that the type information included in the first message is a processing request, the other one of the wireless module and the interface module is configured to generate the second message whose type information is a processing response and whose format is the same as the first message, and to reply the second message to the one of the wireless module and the interface module. a wireless module configured to wirelessly transmit a signal which has been received from a field device, and wirelessly receive a signal which is to be transmitted to the field device; and an interface module which is disposed between the wireless module and the field device, wherein one of the wireless module and the interface module is configured to generate a first message having a predetermined format, the first message includes data and type information, the data is to be transmitted to other one of the wireless module and the interface module, the type information represents a type of the data, and the one of the wireless module and the interface module is configured to transmit the first message to the other one of the wireless module and the interface module, wherein the other one of the wireless module and the interface module is configured to generate a second message in accordance with the type information included in the first message, the second message includes data and type information, the data is to be replied to the one of the wireless module and the interface module, the type information represents a type of the data, and the other one of the wireless module and the interface module is configured to reply the second message to the one of the wireless module and the interface module, wherein in a case that the type information included in the first message represents notifications or instructions, the other one of the wireless module and the interface module is configured to perform processing in accordance with the notifications or the instructions, and do not reply the second massage to the one of the wireless module and the interface module; and wherein in a case that the type information included in the first message is a processing request, the other one of the wireless module and the interface module is configured to generate the second message whose type information is a processing response and whose format is the same as the first message, and to reply the second message to the one of the wireless module and the interface module.