A user terminal device (100, 200), comprising: a first cover and a second cover; a hinge which connects the first cover with the second cover; a flexible display (110, 230) comprises a first display area and a second display area which is larger than the first display area, wherein the flexible display (110, 230) is mounted on the opposite sides of the first cover and the second cover, the flexible display is folded to be divided into the first display area and the second display area when the user terminal device (100, 200) is folded such that the first cover and the second cover face in opposite directions by the hinge; a touch detector configured to detect a user interaction; a folding detector configured to detect at least one of whether the user terminal device (100, 200) is in a folded state and an angle at which the user terminal device (100, 200) is folded; and a controller (130, 290) configured to, based on an event being received while the user terminal device (100, 200) is in the folded state, control the flexible display (110, 230) to display information related to the event on an exposure area (340, 2310, 2330) of the second display area, wherein the event is a call request being received from an external device through a communication unit, and based on the user terminal device (100, 200) being unfolded from the folded state by a predetermined angle, control the flexible display (110, 230) to display a plurality of icons for controlling various function of the telephone call, and in response to the display being completely unfolded while an icon is touched from among the plurality of icons, accept the call request and execute a function corresponding to the touched icon. a first cover and a second cover; a hinge which connects the first cover with the second cover; a flexible display (110, 230) comprises a first display area and a second display area which is larger than the first display area, wherein the flexible display (110, 230) is mounted on the opposite sides of the first cover and the second cover, the flexible display is folded to be divided into the first display area and the second display area when the user terminal device (100, 200) is folded such that the first cover and the second cover face in opposite directions by the hinge; a touch detector configured to detect a user interaction; a folding detector configured to detect at least one of whether the user terminal device (100, 200) is in a folded state and an angle at which the user terminal device (100, 200) is folded; and a controller (130, 290) configured to, based on an event being received while the user terminal device (100, 200) is in the folded state, control the flexible display (110, 230) to display information related to the event on an exposure area (340, 2310, 2330) of the second display area, wherein the event is a call request being received from an external device through a communication unit, and based on the user terminal device (100, 200) being unfolded from the folded state by a predetermined angle, control the flexible display (110, 230) to display a plurality of icons for controlling various function of the telephone call, and in response to the display being completely unfolded while an icon is touched from among the plurality of icons, accept the call request and execute a function corresponding to the touched icon.