A facsimile machine comprising: a user interface unit; a modem unit; a line interface unit to connect the modem unit to a telephone line; a memory storing a self-diagnosis program; and a controller to: receive a self-diagnosis program execution command via the user interface unit, and in response to receiving the execution command, execute the self-diagnosis program to determine a status of the facsimile machine, wherein when the self-diagnosis program is executed by the controller, the controller controls the modem unit and the line interface unit to perform self-diagnosis, and controls the user interface unit to output a self-diagnosis result report detailing whether an error has occurred, wherein to determine whether an internal structure of the facsimile machine operates normally, the controller determines whether an interface between the controller and the modem unit has been established normally via a data exchange using serial communication, and when it is determined that the internal structure of the facsimile machine operates normally, the controller determines whether a connection of the facsimile machine to the telephone line via the line interface unit operates normally. a user interface unit; a modem unit; a line interface unit to connect the modem unit to a telephone line; a memory storing a self-diagnosis program; and a controller to: receive a self-diagnosis program execution command via the user interface unit, and in response to receiving the execution command, execute the self-diagnosis program to determine a status of the facsimile machine, wherein when the self-diagnosis program is executed by the controller, the controller controls the modem unit and the line interface unit to perform self-diagnosis, and controls the user interface unit to output a self-diagnosis result report detailing whether an error has occurred, wherein to determine whether an internal structure of the facsimile machine operates normally, the controller determines whether an interface between the controller and the modem unit has been established normally via a data exchange using serial communication, and when it is determined that the internal structure of the facsimile machine operates normally, the controller determines whether a connection of the facsimile machine to the telephone line via the line interface unit operates normally. receive a self-diagnosis program execution command via the user interface unit, and in response to receiving the execution command, execute the self-diagnosis program to determine a status of the facsimile machine, wherein when the self-diagnosis program is executed by the controller, the controller controls the modem unit and the line interface unit to perform self-diagnosis, and controls the user interface unit to output a self-diagnosis result report detailing whether an error has occurred, wherein to determine whether an internal structure of the facsimile machine operates normally, the controller determines whether an interface between the controller and the modem unit has been established normally via a data exchange using serial communication, and when it is determined that the internal structure of the facsimile machine operates normally, the controller determines whether a connection of the facsimile machine to the telephone line via the line interface unit operates normally.