An input device for receiving operation input of an air conditioner comprising an outdoor unit and an indoor unit, the input device comprising: an input unit comprising four directional buttons (706a, 706b, 706c, 706d), an OK button, a power button, and a back button; a display unit; a communication unit configured to communicate with the indoor unit; an interface unit configured to provide an interface for exchanging data with an external device; and a controller configured to display a home screen comprising a plurality of icon items on the display unit, and transmit temperature information set through a temperature setting item in the home screen to the external device through the interface unit, wherein the controller is configured to display a gray based home screen, when the input device enters a standby mode in response to the operation of the power button, wherein the controller is configured to display an edge of the temperature setting item of the home screen in the standby mode in black, wherein the controller is configured to enter the input device into the operation mode again, display the edge of the temperature setting item in blue, and display the temperature setting item among a plurality of items in the central region in the home screen, when the power button is operated again in the state in which the input device is in the standby mode, wherein the controller is configured to shift and display an operation mode item in the central region, when a leftward button of the four directional buttons (706a, 706b, 706c, 706d) of the input unit is operated in the state in which the temperature setting item is located and focused in the central region of the home screen and the operation mode item is located at a left side of the temperature setting item, and wherein a size of the operation mode item in the central region is larger than a size of the other items. an input unit comprising four directional buttons (706a, 706b, 706c, 706d), an OK button, a power button, and a back button; a display unit; a communication unit configured to communicate with the indoor unit; an interface unit configured to provide an interface for exchanging data with an external device; and a controller configured to display a home screen comprising a plurality of icon items on the display unit, and transmit temperature information set through a temperature setting item in the home screen to the external device through the interface unit, wherein the controller is configured to display a gray based home screen, when the input device enters a standby mode in response to the operation of the power button, wherein the controller is configured to display an edge of the temperature setting item of the home screen in the standby mode in black, wherein the controller is configured to enter the input device into the operation mode again, display the edge of the temperature setting item in blue, and display the temperature setting item among a plurality of items in the central region in the home screen, when the power button is operated again in the state in which the input device is in the standby mode, wherein the controller is configured to shift and display an operation mode item in the central region, when a leftward button of the four directional buttons (706a, 706b, 706c, 706d) of the input unit is operated in the state in which the temperature setting item is located and focused in the central region of the home screen and the operation mode item is located at a left side of the temperature setting item, and wherein a size of the operation mode item in the central region is larger than a size of the other items.