There is provided a fuel cell system which can prevent the drying of a
proton exchange membrane and prevent the generation of liquid droplets at
a hydrogen tank surface which blocks the supply of air, at the same time,
and which includes a hydrogen tank, a fuel cell stack disposed such that
a first air hole thereof faces the hydrogen tank and a second air hole
thereof is open to the atmosphere, and a water holding member provided on
a surface of the hydrogen tank facing the first air hole of the fuel cell
stack, for collecting and holding water generated in the fuel cell stack.