The present invention relates to a method for configuring master/slave boards during the initial booting of a double board, and a board thereof. The method for configuring a master/slave in a double board, according to one embodiment of the present invention, comprises: an input step in which power by means of an initial booting is simultaneously inputted in doubly-configured first and second boards; a generation step in which the first and second boards each generate a random number when the power is inputted; a transmission/receiving step in which the first and second boards each transmit, to each other, the generated random number thereof, and receive, from each other, the random number of the other; and a configuration step in which the first and second boards each configure themselves as a master board or a slave board by comparing the two random numbers that were transmitted/received.