A fuel cell system which allows uniform fuel distribution to respective fuel cells, comprising: a plurality of fuel cells 5 each including an anode 2, a cathode 3 and an electrolyte membrane 4 disposed between the anode 2 and the cathode 3; and a fuel supply flow path 6 branched to supply fuel to each of the fuel cells 5. The sectional area of the fuel supply flow path in the downstream of each branch connection is narrower than that in the upstream. The above-described structure avoids the decrease in the fuel supply pressure due to the reduced sectional area in the downstream of the branch connection. Therefore, the fuel is supplied to the respective fuel cell with uniform pressure.