A display device for converting a voice to a text and displaying the converted text and a method thereof are disclosed. The display device comprises a storage unit configured to store the voice data; a display unit configured to display the text; a sensor unit configured to detect a user input to the display unit; and a processor configured to convert the voice data to the text and display the converted text in the display unit, wherein the processor provides a text preview interface displaying at least a part of the text in the display unit, in response to a first user input, and provides a text output interface displaying the text in the display unit, in response to a second user input, and the text output interface displays the text in accordance with the second user input.