An electronic device comprising: a display unit configured to display, in one screen, a first display area (310; 701) in which a main task is executed and a second display area (320; 702) in which a sub-task is executed; a sensor unit configured to detect a rotation of the electronic device; a camera configured to photograph a user's face located in front of the electronic device; and a controller configured to determine a direction of a user's face relative to the electronic device based on the user's face photographed by the camera, and when the rotation of the electronic device is detected by the sensor unit, to determine a display direction of at least one of the first display area and the second display area based on an angle between a direction of the electronic device and the determined direction of the user's face; wherein the camera is further configured to photograph a movement of a user's eye located in front of the electronic device; and wherein the controller is further configured to: determine a position of a user's sight line on the display by analyzing a movement of the user's eye photographed by the camera, and when the rotation of the electronic device is detected by the sensor unit, display the screen in a state in which the display direction of the screen has been rotated and the one of the first and second display areas corresponding to the determined position of the sight line is expanded to fill an entire screen. a display unit configured to display, in one screen, a first display area (310; 701) in which a main task is executed and a second display area (320; 702) in which a sub-task is executed; a sensor unit configured to detect a rotation of the electronic device; a camera configured to photograph a user's face located in front of the electronic device; and a controller configured to determine a direction of a user's face relative to the electronic device based on the user's face photographed by the camera, and when the rotation of the electronic device is detected by the sensor unit, to determine a display direction of at least one of the first display area and the second display area based on an angle between a direction of the electronic device and the determined direction of the user's face; wherein the camera is further configured to photograph a movement of a user's eye located in front of the electronic device; and wherein the controller is further configured to: determine a position of a user's sight line on the display by analyzing a movement of the user's eye photographed by the camera, and when the rotation of the electronic device is detected by the sensor unit, display the screen in a state in which the display direction of the screen has been rotated and the one of the first and second display areas corresponding to the determined position of the sight line is expanded to fill an entire screen. determine a position of a user's sight line on the display by analyzing a movement of the user's eye photographed by the camera, and when the rotation of the electronic device is detected by the sensor unit, display the screen in a state in which the display direction of the screen has been rotated and the one of the first and second display areas corresponding to the determined position of the sight line is expanded to fill an entire screen.