A method of writing content through a writing input on a touch screen is provided. The method includes displaying written input content according to a writing input detection and identifying whether there is a proofreading mode control, and when there is the proofreading mode control, entering a proofreading mode, displaying the written input content according to the writing input detection, identifying a proofreading mark in the written input content, and applying an editing content corresponding to the proofreading mark, so as to proofread the written content.