A fuel cell stack includes: a first stack including: first unit cells stacked; and a first outer peripheral surface around a first stacking direction of the first unit cells; a second stack that is juxtaposed to the first stack including; second unit cells stacked along the first stacking direction of the first unit cells; and a second outer peripheral surface around a second stacking direction of the second unit cells; an external gas manifold that supplies and discharges a reactant gas to and from the first and second stacks; and an external coolant manifold that supplies and discharges a coolant to and from the first and second stacks.