A fuel cell stack includes a first stack including a plurality of first fuel cells stacked on each other, and a second stack including a plurality of second fuel cells stacked on each other and disposed on one side of the first stack. Each of the first stack and the second stack includes a fuel inlet hole, through which fuel to be supplied to anodes of the respective first and second fuel cells is introduced, a fuel discharge hole, through which the fuel passing through the anodes is discharged, an air inlet hole, through which air to be supplied to cathodes of the respective first and second fuel cells is introduced, and an air discharge hole, through which the air passing through the cathodes is discharged. The fuel cell stack divided into the two stacks increases a charging ratio of hydrogen at the anodes of the respective stacks.