A communication adapter includes: a communication circuit configured to receive and transmit information from and to an external apparatus via a communication network; a memory including a plurality of program storage areas whose stored contents are rewritable; and a controller. When a program update process is started up during execution of a program stored in a first program storage area of the plurality of program storage areas selected at the time of a startup process, the controller executes a process of writing an update program received by the communication circuit from the external apparatus into a second program storage area different from the first program storage area. When the process of writing ends normally, the controller re-executes the startup process with the update program read from the second program storage area.