A portable electronic apparatus comprising: a main body portion including: a display (120, 220), a touch portion configured to detect a user touch; a processor (170, 270); the portable electronic apparatus further comprising: a strap (130, 210) attached to the main body portion, wherein the strap (130, 210) is not included in the main body portion; a sensor included in the strap (130, 210); wherein the processor (170, 270) is configured to: obtain, from the sensor, bending information, including a position and an angle at which the strap (130, 210) is bent, and determine relative positional information between the display (120, 220) and the strap based on the bending information, in response to obtaining the bending information and determining the relative positional information, determine whether the user touch is detected through the touch portion; and when it is determined that the user touch is detected: identify a user interaction based on the bending information and the relative positional information between the display (120, 220) and the strap, and control the display(120, 220) to display a user interface, Ul, element based on the user interaction. a main body portion including: a display (120, 220), a touch portion configured to detect a user touch; a processor (170, 270); a display (120, 220), a touch portion configured to detect a user touch; a processor (170, 270); the portable electronic apparatus further comprising: a strap (130, 210) attached to the main body portion, wherein the strap (130, 210) is not included in the main body portion; a sensor included in the strap (130, 210); a strap (130, 210) attached to the main body portion, wherein the strap (130, 210) is not included in the main body portion; a sensor included in the strap (130, 210); wherein the processor (170, 270) is configured to: obtain, from the sensor, bending information, including a position and an angle at which the strap (130, 210) is bent, and determine relative positional information between the display (120, 220) and the strap based on the bending information, in response to obtaining the bending information and determining the relative positional information, determine whether the user touch is detected through the touch portion; and obtain, from the sensor, bending information, including a position and an angle at which the strap (130, 210) is bent, and determine relative positional information between the display (120, 220) and the strap based on the bending information, in response to obtaining the bending information and determining the relative positional information, determine whether the user touch is detected through the touch portion; and when it is determined that the user touch is detected: identify a user interaction based on the bending information and the relative positional information between the display (120, 220) and the strap, and control the display(120, 220) to display a user interface, Ul, element based on the user interaction. identify a user interaction based on the bending information and the relative positional information between the display (120, 220) and the strap, and control the display(120, 220) to display a user interface, Ul, element based on the user interaction.