Display apparatus, multi display system, and control method are provided. The display apparatus which comprises a display unit displaying an image, the display apparatus include: a storing unit in which information about a maximum resolution of the display unit is stored; a signal processing unit which captures an area of an input image signal of a high resolution, and processes the captured image signal to enable the display unit to display the input image signal if the input image signal has a resolution higher than the maximum resolution of the display unit stored in the storing unit; and an output unit which outputs the image signal input to the signal processing unit to an outside. With this, display apparatus, a multi media system and a control method thereof are capable of displaying an input image signal having resolution higher than a maximum resolution of a display unit.