A computer system and a control method thereof, the computer system including: a processor which executes a program; a communication unit which communicates with an external device; a main body which is provided with the processor. A cover which can be opened and shut with regard to the main body; an open/shut sensor which senses whether the cover is open or shut; and a controller which interrupts an operation of the communication unit if the open/shut sensor senses that the cover is shut.