An electronic device comprising: a touch screen; a microphone; a speaker; and at least one controller configured to: generate memo data including a plurality of objects based on a user's input on the touch screen while recording audio data received from the microphone, wherein an object is an unit of inputting memo having an input time and an input length, synchronize the memo data and the recorded audio data, by mapping index time points in the recorded audio data to the plurality of objects, and store the synchronized memo data and recorded audio data, in response to a request for playback of the recorded audio data: display the plurality of objects of the memo data with a first color, output an audio signal of the recorded audio data using the speaker, and while the audio signal is being output according to a playback time of the recorded audio data, change the first color of the object of the memo data, corresponding to the time point in the recorded audio data that is being played back, to a second color different from the first color, receive a request for selecting an object of the plurality of objects while the recorded audio data is played back and move the playback of the recorded audio data to a point where the object is selected based on an index point of the recorded audio data mapped to the selected object and a position of a touch point on the selected object, wherein the objects include at least one of dots, lines, check marks, letters, symbols and patterns. a touch screen; a microphone; a speaker; and at least one controller configured to: generate memo data including a plurality of objects based on a user's input on the touch screen while recording audio data received from the microphone, wherein an object is an unit of inputting memo having an input time and an input length, synchronize the memo data and the recorded audio data, by mapping index time points in the recorded audio data to the plurality of objects, and store the synchronized memo data and recorded audio data, in response to a request for playback of the recorded audio data: display the plurality of objects of the memo data with a first color, output an audio signal of the recorded audio data using the speaker, and while the audio signal is being output according to a playback time of the recorded audio data, change the first color of the object of the memo data, corresponding to the time point in the recorded audio data that is being played back, to a second color different from the first color, generate memo data including a plurality of objects based on a user's input on the touch screen while recording audio data received from the microphone, wherein an object is an unit of inputting memo having an input time and an input length, synchronize the memo data and the recorded audio data, by mapping index time points in the recorded audio data to the plurality of objects, and store the synchronized memo data and recorded audio data, in response to a request for playback of the recorded audio data: display the plurality of objects of the memo data with a first color, output an audio signal of the recorded audio data using the speaker, and while the audio signal is being output according to a playback time of the recorded audio data, change the first color of the object of the memo data, corresponding to the time point in the recorded audio data that is being played back, to a second color different from the first color, display the plurality of objects of the memo data with a first color, output an audio signal of the recorded audio data using the speaker, and while the audio signal is being output according to a playback time of the recorded audio data, change the first color of the object of the memo data, corresponding to the time point in the recorded audio data that is being played back, to a second color different from the first color, receive a request for selecting an object of the plurality of objects while the recorded audio data is played back and move the playback of the recorded audio data to a point where the object is selected based on an index point of the recorded audio data mapped to the selected object and a position of a touch point on the selected object, wherein the objects include at least one of dots, lines, check marks, letters, symbols and patterns.