Disclosed are a computer system storing with a restoration program and a method of updating the restoration program, the computer system including: a first storage unit in which a predetermined program is installed, a second storage unit in which a restoration program corresponding to the program is stored, a communication unit which communicates with an external server, a user input unit, and a controller which stores an update file corresponding to the program received from the external server in the first storage unit, and updates the program installed in the first storage with the update file, the controller updating the restoration program of the second storage unit with the update file of the first storage unit if receiving a certain key input through the user input unit, and restoring the program on the basis of the updated restoration program.