FUEL CELL SYSTEM

PROBLEM TO BE SOLVED: To eliminate offset generated in a case of a long start-up time of a fuel cell by performing an original point learning of a converter current sensor and performing a zero point adjustment.SOLUTION: A fuel cell system comprises: a cell stack 3 which is formed by laminating a plurality of cells 2; a converter 150 which boosts voltage of the cell stack 3; a switching element SW1 which is provided on the converter 150; and a current sensor CS which measures current flowing from the cell stack 3 to the converter 150. The fuel cell system further comprises learning processing means which makes the current sensor CS to perform an original point learning when the switching element SW1 is under stopping and output voltage Vof the converter 150 is greater than input voltage Vof the converter 150. The original point learning is preferably performed at a time period when it is some time after activation of the fuel cell 1, not immediately after the activation.