FUEL CELL SYSTEM

PROBLEM TO BE SOLVED: To provide a fuel cell system capable of being improved in the precision of the moisture content diagnosis in an electric reaction site of a fuel cell. SOLUTION: The fuel cell system is constituted of: a fuel cell obtained by stacking a plurality of cells 100 each constituted of an electrolyte membrane 101, catalyst layers 102 disposed on both sides of the electrolyte membrane 101, gas diffusion layers 103 disposed on the outsides of the catalyst layers 102, and separators 104 disposed so as to interpose the gas diffusion layers 103; a first reference electrode 108 installed on the electrolyte membrane 101 surface on the hydrogen electrode side; a second reference electrode 109 installed in the catalyst layer 102 on the hydrogen electrode side; a resistance detection means to detect a resistance between the electrolyte membrane 101 and the catalyst layer 102 on the hydrogen electrode side from a current value detected by a current sensor and a potential difference detected by a cell monitor 15; and an internal moisture detection means to diagnose an internal moisture content of the hydrogen electrode side of the cell 100 based on the resistance detected by the resistance detection means. COPYRIGHT: (C)2009,JPO&INPIT