Patent ID: 7718286

Claim:
An abnormality detecting device of a fuel cell system, comprising: a hydrogen off-gas circulation passage for making hydrogen off-gas discharged from a fuel cell flow back to an anode of the fuel cell; a discharge passage for discharging part of the hydrogen off-gas, which is circulated through the hydrogen off-gas circulation passage, from the hydrogen off-gas circulation passage; a hydrogen discharge valve provided in the discharge passage; and an abnormality determining portion for determining whether an abnormality has occurred in opening/closing of the hydrogen discharge valve, further comprising: a gas state quantity detecting portion for detecting a gas state quantity of the hydrogen off-gas, the gas state quantity detecting portion being provided in the discharge passage at a position downstream from the hydrogen discharge valve, wherein the abnormality determining portion determines whether an abnormality has occurred in opening/closing of the hydrogen discharge valve based on the gas state quantity of the hydrogen off-gas.