Disclosed is a field device that transmits and receives data via a fieldbus in accordance with any of a plurality of communication protocols. The field device includes: a control section to give an instruction on a communication protocol to be used for transmitting or receiving data via the fieldbus; and a fieldbus controller including a transmitting and receiving section to transmit and receive data in accordance with any of the plurality of communication protocols, and a switching section to switch between the communication protocols to be used by the transmitting and receiving section based on the instruction from the control section.