A field device according to one aspect of the present invention may include a first processor configured to perform a process of communicating first information used for process control and a process of generating second information including a diagnosis result obtained by performing self-diagnosis of the field device, a second processor including a first wireless unit configured to perform wireless communication, the second processor being configured to request the first processor to read at least the second information and to perform a process of transmitting, from the first wireless unit, the second information obtained through the read request as a wireless signal, and a security unit configured to permit or reject a request made to the first processor by the second processor in accordance with a rule which is specified in advance.