Provided is a display apparatus having an improved structure in which all of current and future personal computer (PC) signals and high definition TV (HDTV) signals as well as normal TV signals can be displayed with optimum picture quality. The display apparatus includes a format converter which inputs a video signal of various specifications, converts the video signal into a video signal having a similar horizontal frequency and outputs the video signal having the similar horizontal frequency, a driver which drives a display unit using the video signal converted through the format converter, and a deflection driver which generates a deflection signal appropriate for a video signal having converted formats based on horizontal and vertical frequencies of the video signal having the converted formats output from the format converter and supplies the deflection signal to the display unit. The display apparatus uses the format converter for converting an input video signal of various specifications into a video signal having a single format, thereby realizing optimum picture quality.