A portable device comprising: a flexible display unit disposed on a front surface of the portable device and extending to at least one side surface of the portable device, wherein at least one end of the flexible display unit is bent, wherein at least one bent end of the flexible display unit is extended to the at least one side surface of the portable device, the flexible display unit including a main display area on the front surface, and a curved auxiliary display area on the at least one side surface, wherein the main display area of the front surface of the portable device and the auxiliary display area of the side surface of the portable device are implemented by one integrally formed flexible display unit; and a controller adapted to: operate the portable device in one of a silent alarm mode in which information is displayed only on the curved auxiliary display area and a general mode in which information is displayed on the main display area and the curved auxiliary display area, wherein, in response to an occurrence of a first event when the main display area is not used in the silent alarm mode, to control the flexible display unit to display information related to the first event only on the curved auxiliary display area, and in response to an occurrence of a second event while providing information associated with an application on the main display area in the general mode, control the flexible display unit to provide information related to the second event on the curved auxiliary display area and provide the information associated with the application on the main display area. a flexible display unit disposed on a front surface of the portable device and extending to at least one side surface of the portable device, wherein at least one end of the flexible display unit is bent, wherein at least one bent end of the flexible display unit is extended to the at least one side surface of the portable device, the flexible display unit including a main display area on the front surface, and a curved auxiliary display area on the at least one side surface, wherein the main display area of the front surface of the portable device and the auxiliary display area of the side surface of the portable device are implemented by one integrally formed flexible display unit; and a controller adapted to: operate the portable device in one of a silent alarm mode in which information is displayed only on the curved auxiliary display area and a general mode in which information is displayed on the main display area and the curved auxiliary display area, wherein, in response to an occurrence of a first event when the main display area is not used in the silent alarm mode, to control the flexible display unit to display information related to the first event only on the curved auxiliary display area, and in response to an occurrence of a second event while providing information associated with an application on the main display area in the general mode, control the flexible display unit to provide information related to the second event on the curved auxiliary display area and provide the information associated with the application on the main display area. operate the portable device in one of a silent alarm mode in which information is displayed only on the curved auxiliary display area and a general mode in which information is displayed on the main display area and the curved auxiliary display area, wherein, in response to an occurrence of a first event when the main display area is not used in the silent alarm mode, to control the flexible display unit to display information related to the first event only on the curved auxiliary display area, and in response to an occurrence of a second event while providing information associated with an application on the main display area in the general mode, control the flexible display unit to provide information related to the second event on the curved auxiliary display area and provide the information associated with the application on the main display area.