Patent ID: 8206863

Claim:
A fuel cell system having a fuel cell, coolant circulating means which circulates a coolant into the fuel cell, a temperature sensor for outlet-temperature detection which detects a temperature of the coolant discharged from the fuel cell, and temperature adjusting means programmed to adjust a temperature of the fuel cell by controlling circulation states of the coolant on the basis of the temperature of the coolant discharged from the fuel cell, comprising: abnormality determining means programmed to determine whether or not the temperature of the coolant discharged from the fuel cell is incapable of being detected by the temperature sensor for outlet-temperature detection; and coolant temperature estimating means which, when the abnormality determining means determines that the temperature of the coolant discharged from the fuel cell is incapable of being detected by the temperature sensor for outlet-temperature detection, is programmed to estimate the temperature of the coolant discharged from the fuel cell on the basis of information relating to a temperature of the coolant flowing into the fuel cell and physical information relating to operating states of the fuel cell, wherein the physical information relating to the operating states of the fuel cell is information relating to a power generation amount of the fuel cell and/or information relating to an amount of reaction gas supplied to the fuel cell.