A solid polymer electrolyte type fuel cell system having a reduced size and weight, which exhibits an improved efficiency. To supply reaction gas to an anode or a cathode, a water lubricated type compressor is employed with the following operational advantages. The face pressure of sliding faces of the water lubricated type compressor, that is the compression ratio and number of revolutions thereof, can be greatly improved, as compared to the conventional oil free type compressor. The compression efficiency is improved by reducing of leakage of reaction gas between the sliding faces. No oil film is formed so as not to deteriorate the battery performance. The size of the water lubricated type compressors can be greatly reduced to about one-third to a half of the conventional oil free type compressor. In addition, the improvement of the compression efficiency and reduction of the friction loss result in a great reduction of driving power. Hence, the fuel cell system with the present arrangement is practical particularly when used as a power supply for driving a vehicle, which is severely required to have a reduced size and weight and to be economical.