An electronic device (101, 201), comprising: a housing; a display (160, 260) exposed through one side of the housing; an input device configured to be detachably attached to or inserted into the housing; a processor (120, 210) located in the housing and electrically connected to the display; a non-volatile memory electrically connected to the processor (120, 210) and configured to store a memo application; and a volatile memory electrically connected to the processor (120, 210), wherein the non-volatile memory is configured to store instructions that, when executed by the processor (120, 210), configure the processor (120, 210) to: while the display is turned off or in a low power state, detect a change of state of the input device from a state in which the input device is attached to the housing to a state in which the input device is detached from the housing; in the low power state, load a first part of the memo application and a second part of the memo application in the volatile memory, in response to the detected change of state of the input device, in the low power state, receive an input on a memo area of the display, which is activated for the memo application, and in response to the input, display an image and/or a text generated by the loaded first part and second part of the memo application on the display in the low power state. a housing; a display (160, 260) exposed through one side of the housing; an input device configured to be detachably attached to or inserted into the housing; a processor (120, 210) located in the housing and electrically connected to the display; a non-volatile memory electrically connected to the processor (120, 210) and configured to store a memo application; and a volatile memory electrically connected to the processor (120, 210), wherein the non-volatile memory is configured to store instructions that, when executed by the processor (120, 210), configure the processor (120, 210) to: while the display is turned off or in a low power state, detect a change of state of the input device from a state in which the input device is attached to the housing to a state in which the input device is detached from the housing; in the low power state, load a first part of the memo application and a second part of the memo application in the volatile memory, in response to the detected change of state of the input device, in the low power state, receive an input on a memo area of the display, which is activated for the memo application, and in response to the input, display an image and/or a text generated by the loaded first part and second part of the memo application on the display in the low power state. while the display is turned off or in a low power state, detect a change of state of the input device from a state in which the input device is attached to the housing to a state in which the input device is detached from the housing; in the low power state, load a first part of the memo application and a second part of the memo application in the volatile memory, in response to the detected change of state of the input device, in the low power state, receive an input on a memo area of the display, which is activated for the memo application, and in response to the input, display an image and/or a text generated by the loaded first part and second part of the memo application on the display in the low power state.